This issue is driving me nuts. I have searched everything i can find with no results. My Client has 3 desktop computers running XP PRO SP3 and the error occurs on all 3 machines. the error occurs when using IE7, IE8, Chrome or Firefox. All are updated latest versions. It occurs with all security\ anrivirus software disabled. When they log onto a secure website requiring an email address and password ithey get an error msg " this is not a valid email address".
This occurs with their domain email addresses -email@example.com- and with a yahoo email address. The thing is it's random. They can lgo into HTTPS sites sometimes but not all times. Realy frustrating. I believe the abling is fine, it is not certified but does pass for misswires and shorts, and they plug directly into a Motorola AT&T dsl router.
I think this might be an issue with the AT&T router or the phone wiring but trying to get AT&T to troubleshoot anything past "you've got an internet connection it must be a desktop issue" response is hard to say the least.
Any ideas or thoughts would be appreciated.