Just google for Mirar and you'll get alot of results for removeing it. It's a type of adware. Here's a link to a google search:
Mirar - Google Search. Good luck getting rid of it. I learned the hard way.
If you need help, try these sites:
Spyware Warrior :: Index CastleCops® » Security Forums SpywareInfo Forum FAQ - SWI Forums
More info on viruses in this thread:
WARNING: Viruses on network you should be aware of!
If your trying to play a file and it tells you to d/l something from the internet, just delete the file and search for something else. You shouldn't have to d/l anything in order to play a file, and definately don't d/l activeX files unless it's from a trusted site and your know why your d/ling it.
For videos, stick to avi's and mpg's. Stay away from wmv's, mov's, and asf files. See
What you should know about WMA & WMV Files