New AVAST INternet Security can't scan files???

[REDACTED]

First, let me be clear... I am a PC  novice. I have seen a number of others with the same issue, but no clear answer. So I hope someone can help me.   I was running AVAST Free and Microsoft security Essentials (for the Firewall) on my PC without problems.  I decided to upgrade to Internet Security.   I removed Security Essentials and then upgraded AVAST.  Once I did this any scan I do (Quick or Full)  says Some Files cannot be accessed.   On the QUICK SCAN  it is about 20 files listed, but no indication that anything else scanned or what the status was.  On the FULL SCAN it is 100s, maybe higher that can't be scanned.  (Majority are manifest files, but others are in the mix)  I did call AVAST for guidance, I was thinking maybe part of Security Essentials was still hiding out and causing this,  AVAST said no, but that for 179.00 they could look at it and help me.  I have no idea if my PC is being scanned and is clean or not.  I wish there was an UNDO button for this.   Thanks in advance for any help! 

If this is an unsolvable problem, then I guess I need to know how to remove AVAST so I can move on to something else.

[schmidthouse]

You could read here, it may put your mind at ease
https://blog.avast.com/2014/02/28/how-do-i-handle-files-that-avast-cant-scan/

[REDACTED]

Well, that helps.  Just want to point out that the warning I get doesn't say anything about a password, nor do they have .png.  Does that change anything for you?

Lastly,  wouldn't AVAST tell me something about what it did scan?   The way it is I have to assume it did not find anything.

Thanks so much for taking time to answer.