Just solved a problem for someone that really had me stumped for a while.

They had one of those all-in-one units from HP, and recently some of the buttons (eg Scan)  had disappeared from the HP Director application. Also, they were unable to access some of the HP software's printing functions, getting error messages like "Unable to load the file "C:Program Files\Hewlett-Packard\Digital Imaging\album\Art\*.bmp". And another interesting symptom was that the HP software was no longer listed in the Start Menu.

After trying all the usual things (uninstalling, reinstalling, registry edits, etc etc), it turns out that the software was reliant on the Windows XP Indexing Service. The following link was the one that pointed me in the right direction:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=736271&admit=-682735245+1173005718497+28353475

I found that the Indexing Service had been disabled as part of a "performance tweak". After I re-enabled it, the album printing functions worked again, no errors. However some of the buttons were still missing from HP Director so I then un/reinstalled the HP software and after this everything was working normally again. Plus the Start Menu now contained the HP software entry.

Very strange, but always a relief when a solution is found.