Tabstrip, running external processes and timing issues

HI, last week I posted a couple of threads (which are already solved) about interacting with a external process from different tabs of a tabstrip control. Generally speaking it works fine, but some times it presents an erratic behaviour, I'll try to explain:
1) Each Tabstrip tab must launch at some point the same dos based app with different parameters. And although I already have a sub that checks for the end of the dos based app, sometimes it doesn´t work right. If I launch the dos process from two differents tabs, I have to wait until both processes finishes to continue (doesn´t matter if the process of tab 1 finishes, tab 1 will wait until the process launch by tab 2 finishes). I don´t know if this is related with the fact that the dos process launched by the tabs is the same.
2)I don't know if this is related wiith issue 1, but in each tab I have a timer control and sometimes it tooks a lot of extra time to activate the timer event. All the controls in each tab should run separately right???? Does anybody has an idea of this beahiour???

Just if somebody wants to check my code, I'm attaching my main form and a couple of modules I use. I couldn´t attach the dos based process cause the file is too big.

Thanks in advance

Alejandro