Some programs don't display user interface

[Marty]

I have a Dell 2400 machine (wifes machine) that has been running quite
well for over 4 years. It is running win XP SP3.

Lately when she starts a program nothing appears to happen.
No user screen is presented. Looking at the task manager the program is
running but the GUI never opened up. This has occurred with Firefox,
Picasa3, Thunderbird and other programs.

When she reboots then all programs start normally.

I have done all of the usual stuff, full virus/malware scans on the
machine. Cleaned up the registry. Defragmented the hard drive.
Cleaned the interior of the machine (some dust but I have seen more).
Nothing in the event logs that points to some sort of error condition.

I can't seem to figure out what the problem could be.

Any ideas about what could be the problem with the machine would
be appreciated.

Marty K

 

[DL]

Boot into safe mode, do the apps that dont require a network connection now
run?
"Cleaned up the registry" unless you really know what you are doing is not a
good idea

 

[Marty]

Cleaned the registry with CCClean. Did this after the problem started
not before.
Good idea will try in safe mode.