Same here only it doesn't happen all the time. I will be surfing and then ads suddenly appear! My filters have been deleted. It will happen every few days.
I tried manually updating the filters everyday to see if it was a problem with the filter updates but it made no difference

I don't know what causes it and I only use ABP and LastPass extensions?
Any help would be appreciated?
PS. chromeupdate is allowed on my pc, I am using Windows 7 own firewall. Also it doesn't happen when my browser is closed, it happens when it is open every so often? I just didn't want to start a new thread as this is similar.