A big problem with my game...Please help!

[zgall1]

I have a bizarre problem with my tournament game and I was wondering if anyone has gone through something like this and how they dealt with it. Over the past few months, I feel like I have gotten really good at picking my spots when bluffing and I have developed a decent intution for when I way ahead and when I am way behind. However, in spots where somebody shows aggression postflop after I have shown aggression preflop (and missed) or when someone raises me at any point in the hand, I seem unable to get away from the hand even though everything is screaming that I'm beat. I usually take 5-10 seconds to make a decision, figure that I'm beat and then, to make things worse, I don't just call their raises, I usually go all-in and get insta-called. I have resorted to making two signs that say "Careful!" and I've hung them over my monitor but I don't know if that is going to be enough. I am not sure why I am doing this but I think it has something to do with showing them I can't be pushed around, even when it is absolutely illogical to do so. Has anyone experienced a problem like this and if so, how have you dealt with it?