Can a virus sneak over a VM machine, to your host?

This question was asked on lockergnome.net:

I will firstly give the other users chance to explain and answer before I make my point of view:

The question was:
Just wondering as I am starting to use VM's and I would just like to be clear on this issue, basically, if you get a virus in your VM will or can it then get onto your main OS? Thanks.

Some answers:
I've heard they can't, and I can see where this idea came from. 
I think you'll be safe, and all considering, unless you used a VM for something specific that's known to be dangerous, you're more likely to get your main OS infected 
well it depends on how you set it up, i use VMware and by default its set up so it cant read any of your files, but you can set it up so you can access your own files through the virtual machine. but as you may imagine, enabling that option will leave your main OS susceptible to any virus or malware you may recieve in your virtual machine... so as long as you have it set up to where it cant read or access any of your files on your main OS you are fine  


Well They sumed it up great, just one thing I have learned. If you share your host files/folders with the VM make it a read only setting for then viruses won't be able to make an copy of themselves on the folder. Also if you test AV's on your VM make sure your host pc Has user account changes on so youl know when that happens, also scan your pc after the test you have run.I recommended Hitmanpro and also Comodo cleaning essentials .If you use your VM for other things, make sure an antivirus is installed. If you run a VM with Linux on I won't bother to worry about viruses.

Are you sure your safe?I use Comodo internet security for my Protection,Comodo protect, Other AV's Clean, No cleaning for Comodo already PROTECTED :)