You must be using the Google Chrome browser and I believe this is a security feature being added to the browser. Malware is basically anything that might get installed on your laptop or PC which tracks information and sends this information back. It sounds like some of the advertisers on this site are using some third party sites to distribute the ads, which are black-flagged by Google as known sources for Malware.
Keep in mind, these are not viruses, so anti-virus software won't detect it, especially if you are using a MAC which most likely won't have anti-virus software installed anyway. It is most likely false-positives being detected, but on a site like this where there are a lot of advertisers, it is more common.
2008 SKY Redline Auto Trans. w/ Spoiler
Techno Grey-Black Top
GMPP Stage 2 Tune
Solo High-Flow Cat/K&N air filter
DDMWorks Backbone/Venom Brace/Kappasphere reBAR
18" Chrome Saturn Rims