Iris Rache, a 68-year-old real estate agent from the District, may describe herself as a technology neophyte, but until last month she had few problems juggling her three online services--America Online for personal e-mail, RCN Corp.'s Erols as a backup and a residential-property database service for work. But then she upgraded her AOL software to the new 5.0 version.

"It said just click here and we'll upgrade you to 5. And so I clicked. And they upgraded me," she remembered. "And all this other stuff got screwed up."

She found that she could no longer log on to Erols. And that the housing database she needed that day to get some information for a client would not connect.

Rache tried calling AOL but gave up after being on hold for what she remembered as "forever." She called tech support for the real estate service, and someone walked her through 40 minutes of troubleshooting to no avail. She wound up waiting a month until a tech-savvy friend poked around her machine and tweaked some settings.

She's got company. Since AOL 5.0 was first released in October, technical-support call centers for major Internet service providers competing with AOL--including EarthLink Network Inc., Prodigy Communications Corp., and AT&T WorldNet--have been bombarded with calls from customers reporting similar problems.

A company official, who did not want to be named, said AOL should reimburse other ISPs for the manpower and resources they have been forced to allocate to help customers reconfigure their computers. He said that AOL had been alerted to the conflicts by its own beta testers months before the company created the millions of 5.0 CD-ROMs in circulation. Two AOL users confirmed that they had reported these flaws while testing early versions of 5.0.

Most complaints appear to mirror Rache's: On a Windows computer, non-AOL Internet software is disabled after they upgrade their AOL service. A few have reported conflicts with virus software and other mysterious problems. Some users have found that they can log on to their other ISP--only to be greeted with a "Would you like to start AOL now?" prompt. And some users using AOL's discount "Bring Your Own Access" plan, in which another Internet provider is used for the actual connection, now have to dial up to AOL--incurring a $2.50-an-hour surcharge under that price plan.

Online "help" bulletin boards on AT&T WorldNet and AOL are filled with irate AOL 5.0 complaints shot through with exclamation points. The debate has even migrated to AOL's nature-photography forum, where nearly 40 percent of the 350 messages listed in the middle of this week talked about Version 5.0 bugs instead of the featured topic.

One message was particularly desperate: "[A]fter installing 5.0 . . . I cannot connect to my websites nor can I connect to my Email. . . . Can someone please help me before I go out of business?"

The problem, according to technology experts, appears to be that AOL's network settings basically hijack Windows computers by overwriting their normal Internet settings in a way that causes other Internet providers' settings and software to stop working.

The result takes different forms depending on what operating system you are using (Windows 95, 98 or NT), what your original setup was, whose software you install first and how you answer a critical question that AOL asks during installation. In particular, answering "yes" to "Would you like this copy of the AOL software to be your default Internet application?" apparently triggers many of the problems.

AOL spokeswoman Anne Bentley said that more than 7 million of AOL's 20 million members have downloaded the new software and that members who have complained "seem to be a relatively small number."

"We have found that a very small number in very unusual circumstances have had problems," she said, adding that the solution is "a really simple fix."

But Bill Kirkner, Prodigy Communications Corp.'s chief technology officer, said that in more than half the cases, remedying the problem is tedious and time-consuming.

"Sure, it is possible to fix all of these things," he said. "But it can make the user's experience unpleasant."

Prodigy, which will be the nation's third-largest ISP, with more than 2.2 million members, after it completes its acquisition of telephone giant SBC Communications Inc.'s Internet subscribers, has had to create a five-page instruction sheet for its technical-support staff.

Kirkner said he can see little reason AOL would choose not to follow industry-standard practices for Internet software in the way it had with previous versions: "This is another example of AOL being the bully on the playground."

But Kurt Rahn, a spokesman for EarthLink, which after a pending merger with Mindspring Enterprises Inc. would be the nation's second-largest Internet provider, after AOL, gives AOL the benefit of the doubt.

"It's not a conscious effort or anything as far as we can tell. They are writing the software for what they want and haven't been able to check that things work with other things," he said. "It's a matter of random conflicts."

Still, AOL's good intentions are of little consolation to frustrated members, who say the company should use have used its much-bragged-about easy-upgrade service to distribute warnings about, and ideally fixes for, potential problems.

Subscriber Steven Way, a psychologist from Paris, Tenn., said, "Each time I wanted to use anything but AOL, I would have to close 5.0, uninstall the adapters and reboot the system." He solved his problem by erasing AOL 5.0 and reinstalling 4.0.

With the year 2000 only a week away, AOL 4.0 users considering an upgrade have an additional worry to ponder: Their current software may need a Web-browser update to fix year 2000 issues, while the company reports 5.0 is fully Y2K-ready.

As for Rache, she says the whole experience has led her to consider switching Internet providers: "Practically everyone is talking me out of AOL."