I have only seen this problem reported a couple of times and we have never really got to the bottom of it. I don't actually think it's a bug because PFE is only attempting to access the path to your FS, via FSUIPC, and the path is returning BLANK !!!
One user said the problem was resolved by rebuilding the PFE database but technically that should not make any difference.
Another user said a reinstall fixed the problem, but again, technically that should not be the case.
My best guess would be it has something to do with your anti virus program or some other security application you may be running. Just the other day I had a user who said PFE kept shutting down without warning, sometimes after only a few seconds and other times after a few minutes. There were no error message and I even connected remotely to his machine but could not fathom it out. He then discovered it was due to his AV.... here's what he wrote:-
Hello Dave! Just wanted to thank you for your support on the issue that I had with PFE deluxe. Apparently, I found the problem. It was my webroot secure anywhere
Anti virus program. It was updated earlier this month, and there is some new software component that was shutting down the PFE program. When I turned the Antivirus program off, PFE works fine. So that was the problem. Again thank you for your time. That concludes this case.
Here's my suggestion.
Reinstall PFE.... no need to unistall first, just install over the top, but make sure your AV and any other security type programs are disabled. Then you should be able to tell your AV program to leave the PFE folder and sub-folders alone. AV programs are getting very sensitive these days and can do some very strange things. Even here I've had my AV delete one of the PFE files and told me it was infected !!!! Go figure.
Anyway, hope that helps and please let me know how you get on.