In my Ubuntu 10.04 installation I twice experienced this problem:
I installed Picasa on wine and it was installed and running perfectly for some time.
Then I experienced when I started Picasa that apparently it started but was never shown on screen.
I checked that the process "Picasa3.exe" was on the list of processes, the status was "sleeping" and "pipe_wait".
When I log on at other users of my Ubuntu installation, Picasa was running like it is supposed to do.
How can I solve this problem?