All the movies are meant to be that big from fraps, as they are uncompressed, this lets you have better frame rates when recording.
1) Open virtual dub
2) Open movie (first part)
3) Append avi segment for each part afterwards (in order)
4) Go to compression and use the following:
You probably have a virus. I recommend using a powerful antivirus such as Superantispyware or Combofix (if its a rootkit)
^- do that
if it continues go find a program called combofix