Login Problems

hi, i have this strange problem, i am hoping for some advice.

from a couple of days ago i started having problems logging in to my piwik installation from my laptop. i have not changed anything, on the server in the installation or on my laptop.

when i access the piwik from my desktop PC i am automatically logged in. however when i try to login from my laptop my username and password are recoginised but i am not logged in and i am just presented with the login screen again.

i reset my password a couple of times now but this is not making any difference i still have the same problem.

does any body have any ideas what is happening here?