Really strange, in like 100% of all errors that I encountered a second error window from the BF2 debugger pops up once the game crashes in windowed mode. Could you see if you have a crashlog.txt in your FH2 folder?
Other than that, any firewall settings on your PC which could prevent BF2 from joining servers? Can you log in on the Account server or have you been using an off-line account without noticing?