Very slow to login and sometimes won't

Hi,

I’ve recently upgraded to the latest version of WordPress and my site has become very slow to log in to and sometimes I can’t get into it at all. I’ve tried disabling all plugins (by renaming the plugins folder) that that has no effect on the problem.

I’m using the Thesis theme.

Any advice most welcome. The blog is at http://www.philipraby.co.uk

Many thanks!

Phil