Q. Is there a way to validate MIBs that fail to import into InterMapper?
A. There is a tool for checking MIBs that give an error when importing into InterMapper. The "Writing Custom SNMP Probes" page recommends the MIB Validator tool from SimpleWeb.
Use it to check that your MIB is syntactically correct. The MIB Validator is available from: http://www.simpleweb.org/ietf/mibs/validate/
If there are syntax errors, you can either tweak the MIB files yourself, or contact the vendor to let them know that they have an error.