1 Who do you host with?
Infinology
2 unix or windows?
UNIX (FreeBSD 4.10)
3 what version of php?
Can't figure this out. I can probably get an answer .... eventually.
4 clean install or upgrade?
Installed all files over 1.3x, database upgrade. Installed Feb 8 patch. Uninstalled and reinstalled PayPal IPN module. Re-pasted API parameters.

5 are you using IPN or PayPal Express?
IPN 'cos PayPal express fails.
6 Do you have 1 or both installed? Meaning, if not using one or the other do you have the other one installed?
Both are installed.
7 is there a pattern or specific country that this happens with?
So far - US only.
8 Live or Sandbox?
Live