I am writing this so that if you ever get this virus you will be able to fix it easily and efficiently instead of spending 8 hours fixing it.
If you notice that when you log on you are no longer able to execute .exe files (executable) and it comes up with an error message saying "the file does not have a program associated with it for performing this action. Create an association in the folder options in control panel" then you have the optix pro 1.1 trojan.
Something to note about this virus is that it has altered the registry and disassociated the EXE file type so that Windows doesn't know how to open it.
You are still able to open the programs indirectly though, for instance, you can't open microsoft word, but you can open a saved document which will open up Word/in Word. The way this works is that Microsoft Word is a .exe (Winword.exe), which the virus stops from opening, but the document is a .doc so it is openable.
The same thing happens with Internet Explorer, opening it directly it is an .exe, but opening a saved webpage, or a help document which is in a webpage, which is a .html will open Internet Explorer so you can use it.
If you have the virus, you need to get it fixed, simply running a virus program wont work at the time, so you must first fix the problem, there is a website which will allow you to download a registry entry which will fix the problem, the website is at http://www.computing.net/security/wwwboard/forum/4646.html the registry entry is the very last responce, number 6, download and run the file. This will allow you to run .exe files. Restart and run a virus scan, AVG is a good one which can be downloaded and used for free and legally from www.grisoft.com
Of course this can all be prevented by keeping your virus definitions updated and check you drives regulary, and being careful about opening .exe files from emails.
Also one more thing, get a good firewall like ZoneAlarm Pro, which can be downloaded from www.zonealarm.com, this is of course totally legal as well.