Your browser sent a request that this server could not understand

Hello,
since today I get the following message:

Bad Request

Your browser sent a request that this server could not understand.
Size of a request header field exceeds server limit.

Cookie: piwik_visitor1=1%3DN2I4MmIxZjQ4MzhiYjRkNDJiYzRkMmFhNjY4MjJjYjc%3D%3A2%3DMTI3NzI...

What can I do?

How many sites do you have in piwik, lots of them you visit?
You could try to clear your cookies to get in there again or , if possible, increase the maximum header size.
Thats probably this issue dev.piwik.org/trac/ticket/409 .

[quote=Thomas Seifert @ Jun 23 2010, 01:39 PM]How many sites do you have in piwik, lots of them you visit?
You could try to clear your cookies to get in there again or , if possible, increase the maximum header size.
Thats probably this issue dev.piwik.org/trac/ticket/409 .[/quote]

There are 36 sites and i visit all of them. Now, after i had cleared the cookies, it work without errors. Yes, it looks like the issue.

thanks!