[saini1987]

problem solved by host. Now you can login logout without any problem

many thanks to blind-eddie who help me a lot.

--------------- Added [DATE]1386990115[/DATE] at [TIME]1386990115[/TIME] ---------------

now they replied that

We had only deleted the session files from the corresponding "session.save" , we had not made any other changes. We had checked and verified that there is no issue with session save path with these domains. So please contact the vBulletin support team to fix this issue, because we do not have much support on application.

means the issue is with vBulletin. please the officials reply here. please.

--------------- Added [DATE]1386993378[/DATE] at [TIME]1386993378[/TIME] ---------------

The problem again started on the forum lol.
I have turned "Add No-Cache HTTP Headers" option to "yes". Is it wise to turn this option yes? The other forum users don't have this option turned on to save bandwidth but i have to turn it on to make my site working fine. Is it wise to turn it to yes? Officials reply.