The scan hanging for 2 hours can indicate hard driver error. That has happened to me. But since you said drive C and D are one physical drive and the separate drive E also hangs, you can probably rule out the disk error unless you have had all three drives for a long long time. If you suspect disk error then run chkdsk and quickly make copies of the important stuff before disk failure screws you over like it did to me.
Does your scan report show anything abnormal? While the scan hangs, what is the current file listed that's being scanned?
