I've been having problems with my cakes bulging between layers and I've also had a few cakes that ended up with "blow outs" after the cake had been sitting out overnight. Here is what I usually do:
Day 1: bake cakes, let cool, wrap in saran wrap, refrigerate or sometimes let sit out on counter
Day 2: level cakes if needed, fill (usually with bc), fill in with additional bc between layers, crumb coat and let sit for at least 15 to 20 mintues, then ice, then either apply final coating of bc or cover with fondant.
Cake is usually picked up on Day 3.
So can you tell from what I'm doing if I'm doing something wrong? I have to figure this out. I had a mini-meltdown today because of this and I can't keep going through this. Any advice or suggestions are appreciated and will be tried.
Thanks,
Yvette
Well, bulging is generally too much filling. When I add a layer, I press down firmly and force out any extra filling.
As for bubbles and blowouts, it is sometimes because the icing doesn't adhere properly to the cake surface. the bubbles in fondant can be pierced with a pin or needle and worked back onto the cake.
If I apply icing to a dry crumb coat, I try to press fairly firmly as I add the icing, to be sure it sticks.
With fondant, if you knead it like bread dough, you will most likely get air bubbles in it - try rolling it over with the heel of your hand instead ( without lifting it as you knead ) ....does that make sense ?? 
I'm probably not using the right words !!
There was someone on here that mentioned that she put a very heavy frying pan on top of her cakes after filling for a few seconds and that works. For the icing to adhere to the cake you could try brushing the cake very lightly with simple syrup or even strained heated and then warm jam before icing it with buttercream or adding fondant...that may help it adhere better. 
If your icing is actually falling off the side of the cake, you may have too much oil in your mix. Trust me, learned this one the hard way!!
I have had this happen to me too! Do you mean because of the cake mix or icing??? I think that what I did was a little too much in both. My icing was chocolate! Thanks for the tip!
Bulging can also happen if the layers aren't supported enough at the edges. I always use a very, very stiff BC to make a dam, then add my filling. You can use the #12 tip or just a coupler without a tip to make the dam. Stack your layers, then dam again from the outside, filling in any open spaces between the layers, then crumb coat and let it settle for 30 mins. or so. The gentle pushes on the layers while stacking also help.
I was having the same problem and then started doing the following
dam (1/4 inch from the edge of the cake) with stiff buttercream using #10 or #12 tip, add the filling making sure not to over fill, fill the gap (between the dam and the edge of the cake) with the same stiff butter cream once the layers are placed, cover with plastic put the pan on the top of the cake and put a 1lb box of conf sugar in the pan, let it sit for 20 minutes or so - this allows the cake and filling to settle, ice as usual. all are tips i picked up on this site. hope it helps.
The damn that you place around the inside may be too thick or too close to the edge of the cake
A dam can be too thick? I use just the coupler not the tip 10 or 12...could I be using too much? Then again I usually have to go back an fill in to the edge of the cake. Maybe I'm placing it too far in also?
The damn that you place around the inside may be too thick or too close to the edge of the cake
Oh I didn't realize too close to the edge could cause bulging too. That could explain why I have this problem occasionally too. It was kind of noticable (at least to me, family either didn't notice or care) on my last fondant-covered cake. Thanks! I'm going to pay more attention to this next time.
If you just started having this problem in the last couple/few months, are you using the 'new' transfat free crisco in your frosting? I had the same problem, air bubbles, frosting falling off the sides of cakes, bulging, and it turned out that the new crisco was the cuprit. I switched to a generic brand that still has trans fats, and it fixed the problem.
(Search the forums for new crisco for more info. This has been a huge problem for many decorators. And make sure you check the nutrition label, even ones that don't say 'trans-fat free' on the front could be, they started packaging the new crisco in the old containers).
I have bulging when my filling is too soft...especially in the summer with the humidity and if ur in San Antonio u mayb in the same boat. I also try to use a thinner layer of filling also, but the softness is what causes my bulging. HTH
I find that I have bulging, blow outs, or icing not adhering to the sides if
1. my buttercream is too soft to dam with, or my dowels are too short and the bulging occurs once the cakes are stacked (bulging)
2. my dam is not wide enough or placed too close or even extending over the edge of the cake (blow outs)
3. my cake is too oily (not sticking)
To remedy these situations I use a stiffer buttercream for my dams, I use just a coupler for applying the dam, and make my dam an even thickness and width inside of the edge of the cake.
I also push down on each level to help secure and it also provides me with the opportunity to do some leveling of tiers at this stage if needed.
This may address some of your problems:
http://www.cakeboss.com/PreventBulging.aspx
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