The newest F5 tablets from Motion Computing have a dual CPU configuration. After setting the tablets up with Windows XP, we noticed that our RFID scan success dropped from 95-100% to around 20-30%. The RFID read function (c# code) returns a "Tag Not Found" error immediately after reading the tag. It beeps like it read ok, then it returns the error. About 3 in 10 times it returns the tag ID correctly.
I rolled one of the tablet's XP HAL back to Uniprocessor and it fixed the issue, however this won't work long term as future service packs will restore the kernel to Multiprocessor and I'll be stuck again. Not to mention it's a pain to do this with 40+ tablets.
Could it be that computers with extemely fast processor(s) scan for the tag too fast after sending the power up signal to the RFID chip?