sanitation problem? - help!!

i'm new to homebrewing and so far i just use a plastic bottling bucket with the airlock lid to ferment my beer, instead of the glass carboy. usually when i brew it, the airlock bubbles some and a bit of foam gets up in there.

the other night i was brewing up a scottish ale and after i put it in the fermenter with the yeast and put the lid on, the brew was fermenting so aggressively that it was causing the lid to pop up in one spot. i tried to correct it as often as i saw it happen, but it still did a few times.

was this normal? was this caused by a sanitation problem? and finally, is my beer still safe to bottle up and drink or is it ruined now?

I would say all of the gasses coming out should prevent any from coming in. I've heard of a lot worse situations tunrning out ok. Hang in there finish up the beer then enjoy!

This is normal for a very vigorous fermentation. Search for blow off tubes...might help. As far as infection, if it tastes good then you should be fine. Take a hydrometer sample and then again in a couple days, if steady, bottle.