How can I get rid of TrojanDownloader:Win32/VB?

A week or so ago, Windows Defender said I had some Trojan viruses and Trojan downloaders on my computer. I tried to do everything on Read and Run Me First, although there were a few things that didn't work. After that the virus scans were clear for one day, and now Windows Defender says I have TrojanDownloader:Win32/VB. Windows Defender doesn't seem able to remove it. Should I go through all the Read and Run Me First Steps again, or is it time to get some help from you?

I don't know how to find out the specs for my computer, but it is fairly new (less than a year old) and uses Windows Vista. It was given to us by my mother-in-law, so we are not the original users (I don't know whether that's relevant or not). We have had it for a month or so, and it never seemed to run very well (just seemed slow for a newish computer), but lately it gets slower and slower until it just isn't doing anything, but if we restart it, it improves. I don't really know what else I should tell you about it.

Here are the things I had problems with when I did Read and Run Me First:
-I uninstalled Java but when I tried to install the new version, nothing happened.
-I couldn't figure out how to empty all quarantine type folders for antivirus and antispyware applications. My antivirus program has 38 files quarantined.
I think I did everything else.

This wasn't part of Read and Run, but somewhere on your website it says to do a backup. When I tried, I got this error message: "Error occurred. Not enough space to save backup files. Free up disk space or change your backup settings." I also keep getting a message that says, "Low disk space. You are running out of disk space on Recovery (D." I don't know what to do about this.

A couple of hours ago, the computer froze up completely, so we shut it down and restarted. When it came back on, there was a black screen that said, "CHKDSK is verifying files..." I don't know what this means. After it finished, the computer seemed to be back to normal.

I don't know what else I should tell you. I'll attach three of the logs to this post, and then the fourth one to another post.

 

I wanted to attach my MGTools log, but I got this message when I opened MGtools.exe:
zip I/O error: permission denied.
zip error: could not create output file (was replacing the original zip file).
access is denied.

I don't know what to do, so I guess I'll try running MGtools again and see if I can get a log to send to you.

I hope I'm doing the right thing:confused

 

Thanks so much for your reply.

Sorry for converting the text logs to Word. I couldn't figure out how to attach them otherwise.

I thought I followed the instructions exactly for MGtools on Vista. I did run it and got a log, but the next day when I wanted to attach the log to my post, I got the error message I told you about. I don't know what I did wrong.

Since I last posted, my computer has totally crashed. When I try to start it, I get a black screen that says:
"Windows Error Recovery
Windows failed to start. A recent hardware or software change might be the cause....
Launch startup repair (recommended)
Start Windows normally"
I chose the "launch startup repair" option. Then I get a "Windows is loading files" message for a few seconds, and then a blue screen that says:
"A problem has been detected and Windows has been shut down to prevent damage to your computer...."

Is there anything I can do now? I am using my daughter's laptop now, so will keep checking for a reply from you. Thanks again! \