Audio slow down and noise on playback

New user here. I've only so far recorded a couple of tracks for test purposes. Just using a single mic thru a Delta 1010LT set to 128 samples, 44.1. The 3 or so minute track I recorded plays back fine, and with lots of plugs (except for the Sony Acoustic Mirror DX plug, it causes stuttering). But when I audition a .Wav file in media explorer, or when I insert it in a new track, it'll play fine for a few seconds (this amount seems to be random) and then I'll hear a sound kind of like RF interference and the audio will also slow down almost like it's the wrong sample rate (but it's not, the original file was recorded in Sonar at 44.1). FYI, I'm using XP on a Pentium D machine with 2G Ram, 2 SATA HD's. For monitoring, I'm using theS/PDIF outs into an ART DI/O into my monitors. This also happens in SoundForge 9. Am I missing something obvious here?

I've done that. All the way up to the limit. 2k something...

Are you using Wave drivers instead of ASIO drivers?

Nope, ASIO on my Delta 1010. Now when I do change the buffering via the Delta panel, I can hear the "pitch" of the stuttering noise changing proportionately, FWIW. Also, my primary HD is SATA, my write HD is SATA and the drive I'm accessing the file(s) from is IDE, if that matters, but me thinks it shouldn't, because even after I import the file into Reaper, where it would then reside...hmmm, I don't know exactly where it does reside then, is it still "streaming" the file from the source drive?...it still stutters.

Do you have any other sound card options you can try?I have an E-mu 404 PCI card but I mainly use the in built Toneport sound card in my Line6 GX Di box in Reaper.Also my USB powered speakers have a sound card so in effect I have 3 sound cards to choose from. It could be a card setting.My system is a now old single core AMD 3800+ with 1 gig of RAM and one 7,200 rpm 40 gig IDE drive. Also unless you are already using it try ASIO4All for free,

Also, I just did a windows update, and there were about 23 updates including SP3. Any known issues here?

Try this (allthough I don't know, whether this is the right approach): Go to the main menu "File -> Project settings" and tick on the "Audio Settings"-tab "Project sample rate" normally it's set to 44100, leave it, if your audio-files have the same. -Data

I don't know if that's the problem as audio acts the same way in SoundForge.

Mike,ohave you tried the "real time help line"for Reaper. Maybe somone there can take you step by step thru your problem. Bardo

"real time help line"? what is that?