Problems logging into admin account

[flashgordon]

I currently have severe problems administering my forum.
It started today that I had to login twice to get into the forum. When I tried to log into my admin account, it took about 10 attempts to get in.
Now it has become even worse: I can log in after some failed attempts (I get to the redirection page - as usual -, but then am redirected to the login prompt again) I can not make any action without being prompted to log in again.

What can I do? I've made no changes whats-o-ever, it just started this morning! (I run vbulletin 3.5.4)
I already tried deleting the browser's cache and the forum cookies, but it didn't work!

[Floris]

Upload the tools.php file and reset the cookie path and domain. And check the config.php file to make sure the cookie prefix is a simple and short word like bb or vb or forum - and doesn't contain spaces or weird ascii characters.

Delete the cookies from your hard drive and make sure that no third party program is blocking javascript or cookies on your domain.

[flashgordon]

Thanks for the reply, Floris.

I've found the reason, but I still don't know what I can do:

I am on a university network and have a monthly download restriction of 5GB. After I reached this limit, I can still surf the web, but behind the university's proxy.
This proxy obviously causes the problems with me being logged out of the forum at what seems to be random intervalls. Sometimes I get redirected after the login to the login screen, sometimes I can switch some settings in the administrator panel, before I have to login again.

Can I influence this by any means within vbulletin's settings? Other sites have not shown this behaviour so far.

[Floris]

Not sure, especially as the proxy obviousliy does things to work against you.