Bloomberg Keyboard Problems

We are having problems with Bloomberg keyboards on a several workstations (Compaq DC7100 and DC7700). The PCs keep ?loosing? Bloomberg keyboards once in a while. Unplugging and plugging the keyboard fixes the problem. The Bloomberg Techs have been on sigh, but couldn?t resolve the problem. They just updated the keyboard drivers. I run the HP diagnostic CD, but didn?t find any hardware problems. This happens to both types of Bloomberg keyboards. The keyboards have been replaced several times. I also checked the PCs for spyware. Has anyone experienced a problem like this or have any suggestions on how to resolve it?