ok thanks for the quick response, here goes.
for trackir 4 I have lots the same as this. this is the first.
Event Type:	Error
Event Source:	Application Error
Event Category:	None
Event ID:	1000
Date:		25/04/2012
Time:		5:25:28 PM
User:		N/A
Computer:	OWNER
Description:
Faulting application trackir.exe, version 0.0.0.0, faulting module cameradll.dll, version 3.2.38.0, fault address 0x000193c8.
For more information, see Help and Support Center at 
http://go.microsoft.com/fwlink/events.asp.
Data:
0000: 41 70 70 6c 69 63 61 74   Applicat
0008: 69 6f 6e 20 46 61 69 6c   ion Fail
0010: 75 72 65 20 20 74 72 61   ure  tra
0018: 63 6b 69 72 2e 65 78 65   ckir.exe
0020: 20 30 2e 30 2e 30 2e 30    0.0.0.0
0028: 20 69 6e 20 63 61 6d 65    in came
0030: 72 61 64 6c 6c 2e 64 6c   radll.dl
0038: 6c 20 33 2e 32 2e 33 38   l 3.2.38
0040: 2e 30 20 61 74 20 6f 66   .0 at of
0048: 66 73 65 74 20 30 30 30   fset 000
0050: 31 39 33 63 38 0d 0a      193c8.. 
For trackir 5 I get these;
Event Type:	Error
Event Source:	Application Error
Event Category:	None
Event ID:	1000
Date:		26/04/2012
Time:		2:01:06 PM
User:		N/A
Computer:	OWNER
Description:
Faulting application trackir5.exe, version 5.1.0.300, faulting module atioglxx.dll, version 6.14.10.11251, fault address 0x00cf61fc.
For more information, see Help and Support Center at 
http://go.microsoft.com/fwlink/events.asp.
Data:
0000: 41 70 70 6c 69 63 61 74   Applicat
0008: 69 6f 6e 20 46 61 69 6c   ion Fail
0010: 75 72 65 20 20 74 72 61   ure  tra
0018: 63 6b 69 72 35 2e 65 78   ckir5.ex
0020: 65 20 35 2e 31 2e 30 2e   e 5.1.0.
0028: 33 30 30 20 69 6e 20 61   300 in a
0030: 74 69 6f 67 6c 78 78 2e   tioglxx.
0038: 64 6c 6c 20 36 2e 31 34   dll 6.14
0040: 2e 31 30 2e 31 31 32 35   .10.1125
0048: 31 20 61 74 20 6f 66 66   1 at off
0050: 73 65 74 20 30 30 63 66   set 00cf
0058: 36 31 66 63 0d 0a         61fc..  
I can open trackir 5 in safe mode, but get one light on the camera, and then a warning that the DX (I think, from memory) something can't be initialised, and then the crash.
Trackir 4 has worked without a problem for at least 3 weeks prior to now.