PMDG 737NG CTD when online

Hi everyone!Since I reinstalled both WinXP, FS9.1 and PMDG 737NG, I've been experiencing notorious CTDs with both 737-700 and 737-800. It is usually the very beginning of my flight: starting to taxi, taxiing, take off... Either the FS window becomes black while FSInn or SqBox continue sending and receiving voice and then I get an error message, or the nose gear "brakes" and the plane crashes on ground.I'm using ActiveSky 6.5, FSUIPC 3.75 (registered), FS RealTime and XSquawkBox for MSFS. For my online flights i usually use FSCoPilot 1.2 and FSInn 1.6, but I also tried it with SquawkBox 3. It crashes with both online flight utilities.I've just tried an offline flight with the same utilities except FSInn/SqBox, of course. The flight was perfect!So, it seems that FSInn/SqBox cause the CTD. But why both of them? Is there any common thing about them that could cause my CTDs?Can it be the FSUIPC? Previously I used an older FSUIPC version, the 3.73, and it was better, at least there were no permanent crashes.I'm using two sound cards: an onboard Realtek AC888 (for ATC talk) and a Creative Audigy SE (for all other FS sounds) with the most recent drivers. I've obviously been using only one of them during my offline flight, because there's been no ATC. Can the cards or divers incompatibility be the reason for all that?I would appreciate any comment or advice. Thanx in advance!