Had a user with a windows xp laptop, that would not show any dialog boxes. The computer was pretty slow, but you could open word, click save and nothing would happen. Then, you’d click the X in the upper left and would be prompted if you wanted to save the file. If you said yes, nothing would happen. And any program that would normally bring up a dialog box would do the same thing. Another symptom was the acrobat was exceptionally slow to open.
The problem was that there were over 33,000 files in the TEMP/TMP directory. After deleting all these files, everything worked fine. The majority of these files were named AcrXXXX.tmp, so there must have been a renegade acrobat process that didn’t close properly.