Sounds like you're using a browser with ad-blocking enabled whilst your mate isn't. Unblocked you get a couple of ads at the very top to the right of "PPRuNe", another banner immediately above the forum listings/messages & one down the right side of the forum listings/messages.
Which browser are you using?
The "related search" pop-up sounds like it might be the "webcake" thing described here:
Related search left side popup - WorldStart Tech & Computer Help Forums
You may have acquired it as a side load when installing another program.