Bugcheck when running the Driver Verifier

Hello. I'm part of a company that uses your device extensively for a significant part of our customers; lately we have experienced some stability problems (computers freezing at seemingly random frequency, impossible to reproduce "in lab").
While investigating this, my first culprit was obviously a faulty driver, so I activated the Driver Verifier. I found out that whenever I call UUIRTTransmitIR, the Verifier raises a bugcheck, code 0xc9 (DRIVER_VERIFIER_IOMANAGER_VIOLATION) with param #1 being 7 ("The driver called IoCompleteRequest while its cancel routine was still set.").
Of course, I can't say right now if this is the cause for the root problem (freezes) but even if it isn't, it's obviously preventing me from investigating further
Did anyone else had this kind of problems ? We're running XP Pro SP2, fully patched, with Intel Core2 Quad CPUs.
TIA
While investigating this, my first culprit was obviously a faulty driver, so I activated the Driver Verifier. I found out that whenever I call UUIRTTransmitIR, the Verifier raises a bugcheck, code 0xc9 (DRIVER_VERIFIER_IOMANAGER_VIOLATION) with param #1 being 7 ("The driver called IoCompleteRequest while its cancel routine was still set.").
Of course, I can't say right now if this is the cause for the root problem (freezes) but even if it isn't, it's obviously preventing me from investigating further

Did anyone else had this kind of problems ? We're running XP Pro SP2, fully patched, with Intel Core2 Quad CPUs.
TIA