Need help on scalling up an application?

Hi,
I have this scenario:
1. One main application (vb type exe) it's used to launch more ActiveX exe components that perform a job with msmq (read/write messages ...).
2. Each ActiveX component will use few other components (ActiveX dll-installed on MTS)

I tryied this application on diferrent computers configurations, but there is a low limit of the no of ActiveX exe processes that are able to run into the same time. I can launch any no of activex exe's (I tried with 20) but only 8-9 of them are efectivelly working; all the others wait until one that was working finish his job and then start working.
I tryied this application on servers with 512M ram & 1 proc, and 1G Ram & 2 proc, And the result it's tha same.
It seems that the limitation does not came from the configuration of the machine.
If you have any ideea of who may create this limitation, please reply.
Proceses involved: MTS, MSMQ & my application

Thank you,

Sorin