Did you delete all remainders of your current Installation of BF2 as described? Did you delete the entries in the registry?
If yes, I'm clueless. Then it might be just everything. Like outdates drivers for the mainboard, a missing Microsoft update or a certain microsoft update too much, viruses, you see, it gets speculative. If other games don't run either, I'd just re-install the operating system, I guess. Sorry to say.