AVG Free Edition

Hi

Is your malwarebytes the full paid for version that runs in the background or the free version that runs on demand?

Did you notice the startup slow as soon as you installed AVG 2011?
Did you fully uninstall a previous Antivirus (what was it btw) before installing AVG2011 as old left over files can cause issues?

What Windows Version and Service Pack are you using?

I would try this and fully uninstall AVG 2011 and even run the AVG cleanup tool HERE, then reboot and is your PC quicker on startup? if so then think of a different Antivirus application as of late on a few friends PCs I have noticed that AVG is a bit heavy on resources at startup, likely due to the amount of scanning components now included, I moved friends to Microsoft Security Essentials and boot was fine, I use it on my laptop and netbook.

If its no different after uninstalling AVG then we need to then look into another startup app causing the problem, so boot into Safe Mode (F8 at boot and choose Safe Mode with Networking) and is it any quicker?

if it is then what are your startups and you can follow the small guide below to get this list to attach as noted.