GR4 startup freezes computer, VST and standalone

I've been using GR4 since the free update for recent GR3 purchasers became available. Today, all of a sudden I cannot use it.

Trying to load it as a VST will freeze my computer. Windows Task Manager will show FL.exe (FL Studio) at 99% CPU. Trying to open the standalone has the same result, except Guitar Rig 4.exe shows up in the Task Manager at 99% CPU.

FL Studio projects that I previously saved with GR4 will open and play as long as the GR4 VST is not visible. You can hear the GR4 effect on the guitar. However, if I try to maximize the GR4 window, FL Studio freezes up and shows 99% CPU. Also if I try to remove the GR4 VST effect from the mixer, FL Studio freezes up.

After CPU hits 99%, the song will continue to play and you can still hear GR4 as an effect, but obviously my computer slows to a crawl. The song will continue to play with the GR4 effect until I can finally get FL Studio to shut down.

I still have GR3 installed. It still works fine.

I tried uninstalling GR4 and reinstalling, no help (just used the standard uninstaller and reinstaller, I didn't go ahead and wipe out all traces of GR4). I also tried system restore to an earlier point, it did not help.

I am using Windows XP if that helps.

P.S. What is NIHardwareService.exe?
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EDIT:

Problem fixed. Here's what I did, not sure which part fixed it.

First, I reinstalled my Audio Kontrol 1 drivers. For some reason the drivers were listed twice in installed programs under slightly different names. I completely wiped all all traces of the AK1 software and drivers and reinstalled. No idea how or why this would affect GR4, it probably didn't.

Second, I completely wiped out all traces of GR4 and reinstalled. At least I thought I wiped out all traces, but somehow it remembered my custom presets, maybe it found the backups I made?

Third, the GR4 installation says to make sure all hardware is disconnected so when I reinstalled I disconnected the Audio Kontrol from the USB. I thought by hardware it meant any Rig Kontrol hardware but I disconnected the AK1 anyway.

Not sure which procedure made the difference, but anyway, it's working now.

 

>)