bad recording sound

set up is: signal is tape out from Krell preamp, to usb soundblaster, via belkin gold usb cable to new dell laptop running windows 7 64 bit

recording vinyl (basis gold debut turntable, Koetsu IV) into audacity 2.03. To allow multitasking, I record the vinyl onto the laptop, save the data, and transfer the aup file and data directory on my hardwire (cat 7 cable) network, onto a dell workstation, windows 7, 64 bit, 8 gig RAM.

I use the workstatoin to process the files (automatic followed by manual de-click), name the individual tracks and export to high quality flac files.
On two occasions, the flac files sounded like absolute garbage (JC River media center 18) - like on a bad transistor radio. The processed data files also sounded bad (in Audacity)

I then went back to the original files on the laptop - one sounded OK, the other sounded as bad as the others.

Concerning the laptop; there was no clipping, no reason i could see for a bad recording. when I recopied the viny - without changing any settings- sounded fine.
Any ideas what can cause a bad recording? (entire LP, both sides)

concering the workstation: are there are any sensitive points in the copying/processing/saving process that require sole use of the computer by audacity and during which I should refrain from multitasking?.

I also tried varying degrees of aggressiveness in click/pop removal - didnt seem to make a difference

tha nks

Real time data transfer over USB can be highly sensitive to multitasking. It only requires CPU load to hit a high level for a fraction of a second to completely screw up the recording. USB was not originally designed for continuous, time critical data, so it needs to be handled carefully and is often the weak point in the system. Once the capture is done, there are unlikely to be problems multi-tasking.