Can't install Mallwarebytes

[got ammo?]

I get this error when I try to install Malwarebytes:

Unable to execute file in the temporary directory. Setup aborted.

Error 5: Access is denied

I am running windows Vista 32bit Ultimate. I downloaded the exe to my desktop and tried to run it from there and got that error. I tried "run as administrator" and still got the error. I tried to run it from the download instead of saving and got the same error. I downloaded it to a folder under my user name and tried to run it from there and go the same error. I downloaded it and installed it on my work laptop this morning and it worked great! Found some stuff that Comodo and Spyhunter3 missed. I don't think I have any infections on this computer and just thought I would install it and scan to be safe. Hopefully it is something else not allowing me to install it and not a virus. Thanks in advance for any help.

[GT500]

The last time I saw this error, the user was running OnlineArmor, and simply turning off OnlineArmor solved the issue.

What security software are you using? There's most likely something blocking the file from executing to it's temp dir.

[got ammo?]

I am running Comodo Internet Security, and SpyHunter3. I will turn them both off and see if it works.

[got ammo?]

That worked, thanks!

[GT500]

That worked, thanks!

Probably Comodo's Defense+ (another security product you have to be a security expert to use).

[Nathan Volle]

I can't open Malwarebytes on my computer (XP), once it seemed to properly install. This is the first time I have tried to use it. It shows in the program menu with the Malwarebyte icon, but when I click on it, the hourglass runs for a few seconds and then nothing happens. I think it should be something VERY simple that a beginner like me doesn't know. Any help? Nathan Volle