Hi Rick,
That's very strange - I wonder if there is a chipset incompatiblity with that particular device. Do you know if the Symbol MK500 has full ARMv4i support? (I believe it has an XScale processor - either PXA270 or PXA272?) Are you using the ARMv4i ODBC files in version 9 as well for this device?
Have you tried moving the DLL out from underneath the \Windows directory? Perhaps there's an additional permission that Symbol has added to that area.
Jeff Albion
SAP Active Global Support