I changed ISPs a year ago for two weeks, and had this problem. They had serious lag delays in service sometimes (not enough servers) and SL would quit. That might be your problem. With My current ISP, being logged out unexpectedly happens maybe only once every month or so, usually some other Firestorm bug.

Hello, and thank you for reporting the issue regarding constant logouts. This problem has been brought up by another resident in the past, and we are merging your comments to help address it more efficiently. We understand how frustrating it can be to get logged out unexpectedly, especially during conversations or activities. While we don't have an estimate on when this issue might be resolved, please keep an eye on future updates. Your input is invaluable, and we appreciate your patience and continued support of Second Life. Thank you!