Well I don't have this issue with version 7.5.8.
Using ie or firefox.
At least with three sites I have updated as well as here.
Yes with the 7 day expire for ie, but not while browsing the forum.
I would suggest to open a support ticket. So at least it gets officially documented.
Possibly there is a issue with the installation and your current server configuration.
Or you performed some short cuts with the install/upgrade script.
Now as far as the lost password feature.
I have noticed that if you copy/paste.
There is a extra space added.
