ever since upgrading to MT4 build 203 i have gotten 'could not launch compiler' message. i've had to re-install MT4 for each instance of MT4 i have on my computer. but then it happens again. so far it has occured 3 times and each time i've had to re-install MT4. what gives?

Funny enough, I just had this same exact problem. I thought it was my pc. After some short investigation I found it was due to the upgrade.

So, I went to the mt4 brokers website and downloaded the latest .exe file from there. Next, I manually re-installed the corrupt compiler terminals copying over EAs etc. It is a long process.

I wish the guys at Metaquotes would thoroughly test each update, even with beta testers before releasing them.

here is another clue. i looked into the mt 4 directories and found that the compiler was missing. for some reason it just vanished on my installations of MT4. what i'm doing now is saving a copy of the compiler so that if it occurs again all i have to do is copy/paste the editor into the mt4 directory without having to reinstall the whole thing. worked!