first of all, I have to say that all worked fine since this morning. I haven't changed anything, maybe it depends on one of the latest automatic update.
Before today, when I clicked on change user (start > disconnect > change user) and chose another user, xp would let me in the other account. Now the account is loaded for a second and then I am sent to the initial screen again (the one where all account are shown): it's like XP won't allow more than one user desktop to be open at a time.
Another thing that I noticed is that there is no more indication of how many programs are running under a certain account (before it would say "x programs are running" and "y mail messages are waiting" or such things).
Basically, XP won't let me in other accounts unless I completely disconnect the first user.
How can I solve this?