Prvdi.exe and 127021.exe are evil siblings in the TIBS
Dialer spyware. The MSAS beta finds this spyware but does
not remove it, though it claims to.
Here's how to remove the TIBS dialer manually:
1. Go to Task Manager and end all processes with the file
names above.
2. Go to Search, and find, delete, and empty Recycle Bin
of the file names above. There may be more than one
instance of each file on your computer.
3. Go into the registry and find and delete all
references to the file names above. Edit the registry
with caution.
4. Do a "hard boot" by either unplugging your PC or
holding the on/off button for a few seconds. Do not shut
down normally. It's ugly, but this is the key to success.
5. After starting again, delete any shortcuts placed by
the spyware on your desktop (some versions place a "Sex"
shortcut icon on the desktop; just delete it).
This is the only solution I've found to actually work.
MSAS isn't quite enough.
Good luck.