Using a different computer, download MBAM.
Burn the .exe file to a cd OR copy it to a flash drive.
Try to install from the cd or flash drive.
It's recommended that you update MBAM definitions before running it. If you cannot get the definitions to update, run the scan. Reboot if needed, then try to update. If it updates, run it once more.
If you cannot get it installed, change the name of the .exe file to something else.
Whatever you use to rename it, just make sure you include .exe in the name.
edit to add: I have to leave for a while. Do what you can and post back with results, problems, or concerns.
A malware removal expert might see this topic, and one of them can continue to help you.
In order for you to be sure you are receiving qualified help, please read this, particularly paragraph 3. Even though it's in the Am I Infected? forum, it applies here with regards to instructions and who is helping you. http://www.bleepingcomputer.com/forums/t/182397/am-i-infected-what-do-i-do-how-do-i-get-help-who-is-helping-me/
Edited by Queen-Evie, 21 April 2009 - 11:27 AM.