Thunder B., FF won't launch, etc.

Problems:

1. Fire Fox won't launch
2. Thunderbird won't launch
3. Clam antivirus will not connect to get virus defs.

All my other Portable Apps. will launch correctly.

I have downloaded and installed each of the problem apps. several times. The same problems continue.

I use Portable Apps Base, and a PNY, 1 GB thumb drive.

Any ideas? I am frustrated.