[unc13bud]

"the X-Fi is older than around 4 years old."

and gta 4 came out in 2008, which is why rockstar only does technical support on xp3 and vista gat 4 installations

[mkey82]

I have a suggestion and a question:

1. how fresh is your OS installation? Have you changed any hardware after you did your last fresh install?
2. have you tried taking that sound card out? GTAIV is known to have some problems with sound cards and what you're experiencing sounds a lot like a conflict in the background.