Does anyone have experience working with a BB device with a Smart card reader?

I'm intermittely get an MDS error "An error occurred on the MDS causing this query to fail". when wirelessly searching for certificates to download. Most of the time I can retrieve the certificate. It is either hit or miss.

I'm using BES 4.1.5, OS 4.2, latest version for the smart card reader and SMIME package. Configurations on the BES to allow certificate retrival is set accordingly.

Any ideas?