There is no way to stop MC analysing an inserted optical disc. On my HTPC it even checks the disc drive regularly if the PC is on, or at least I think it is MC making the drive led light up. Even if you don't play a disc, MC creates a record for it in its internal CD Database, and will look up the disc on its online YADB database, collecting metadata. That is why it is doing the analysis, I think.
The analysis often isn't very quick, but it shouldn't get stuck and never stop. It sounds like you have an internal optical drive in an external enclosure, so is that enclosure connected via USB or eSATA, or what? If USB, it could be the USB driver that is the issue. Or just the driver for the optical drive itself. Sometimes they don't like being in an external enclosure.
Turn on MC logging, insert a disc, look for issues in the log and in Windows logs, memory and CPU usage. Only send logs if someone asks you for them. Have a look yourself first.