All plugin upgrades fail after 2.8 upgrade

I have recently upgraded to wordpress 2.8. I did a manual update, but now no plugin upgrades work. I have tried deactivating and reactivating al, but it still doesn’t work.

I get a url like

https://blog.jjtcomputing.co.uk/wp-admin/update.php?action=upgrade-plugin&plugin=google-sitemap-generator/sitemap.php&_wpnonce=xxxxxxxxx

which just times out after asking for a password and ftp details