Full scan always fails on my Windows PC

I started a full system scan a few hours ago, using Avira Free Security. I thought it would be wise to post my questions while the scan is in progress, since it always crashes at some point. As usual, the scanning percentage reached 30% very quickly, and it stays at 30% while the software starts checking all of my files. At this moment, 1134257 items have been scanned and 2 threats have been detected. If this scan runs the same way as all of my previous attempts, it will crash some time in the next 12 hours. If it doesn't crash, great, because I know how to proceed with flagged files. since the odds favor a crash, I have a few questions:

1. In the event of a crash, is there still I log that I can review with a text editor in order to identify and address any threats identified so far? If yes, how can I find that log? (I won't be surprised if the log gets destroyed when a scan crashes, but I'm keeping my fingers crossed.)

2. My computer has two physical drives C: and G: My CD drive is D: and I always have four or five logical drives mapped in order to simulate development environments for some of my clients. As an example, I issue the DOS command "SUBST t: c:\tdrive" during startup to emulate the environment of one client that runs their application on a drive that has been mapped as T:  My question is, is the Avira scanning process "smart" enough to understand the difference between physical drives and logically mapped drives so that the physical drives can be scanned and the logical drives ignored? If not, then I would most likely turn off my mappings before attempting a full scan, to avoid redundancy.

3. Can I duplicate the functionality of a full scan by executing several of your preprogrammed partial scans, one after another? If yes, what scans would I want to perform? 

4. At the bottom of the Full System Scan display, I see a clickable BACK button and a clickable CANCEL link. If I click either of these, will I lose all information related to the scan in progress? I'm really hoping you're going to tell me that clicking BACK will preserve information the scan gathered in the last few hours and take me to an interface that will allow me to deal with the two threats.

Thanks in advance.