[Powerlord]

This may have been fixed in the most recent Source engine update, but that update hasn't been pushed to CS:S yet.

I know I was getting this error every time I was forced to download more than a few files in TF2 prior to the update last week Tuesday, but it has worked fine since then.

As for SOLID_VPHYSICS, I seem to recall seeing errors like those even on Valve maps.