WordPress rejets my password every time.

I am finding that my WordPress site is constantly forgetting my password. It’ll work fine for a few days and then out of the blue it’ll refuse to authenticate with the same password. I’ll then have to go through the lost password routine to get back in. I do that, and it works. I then change the automatically generated password to something else and it seems to accept it – until I try to log in with it and it’s refused again. In one instance it did accept the changed password at login for few days and then out of the blue started rejecting it once again.

Mine is a self-hosted WordPress installation so I guess it’s more a matter for me and my hosting service than it is for WordPress, right?