Peninsular war battle CTD

Game played fine for 90 minutes.

well into a peninsular war Spanish campaign.

fighting a mega battle - full stack defending Valladolid vs 2 French full-stacks.
battle going OK - killed both enemy generals. but infantry being outflanked.

anyway got this CTD - this is the report from the win7 event viewer:

Spoiler Alert, click show to read: 

Log Name: Application
Source: Application Error
Date: 10/07/2010 23:41:47
Event ID: 1000
Task Category: (100)
Level: Error
Keywords: Classic
xxxxxxxxxxxxxxxxxxxxx
Description:
Faulting application name: Napoleon.exe, version: 1.3.0.0, time stamp: 0x4c2b2f64
Faulting module name: mss32.dll, version: 7.2.6.0, time stamp: 0x49efbdd2
Exception code: 0xc0000005
Fault offset: 0x0002eaa9
Faulting process id: 0xe10
Faulting application start time: 0x01cb2075ed6e4aab
Faulting application path: c:\program files (x86)\steam\steamapps\common\napoleon total war\Napoleon.exe
Faulting module path: c:\program files (x86)\steam\steamapps\common\napoleon total war\mss32.dll
Report Id: 51c8ac3e-8c74-11df-bc74-00221588ac20

looks like a miles sound system crash (mss32.dll)

any ideas?

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system E8400 core 2 duo; 4GB RAM; HD4850 graphics, creative titaniuim prof sound card.
run ccleaner on regular basis.
have new 650W PSU.
WIn7 64-bit

have been playing NTW and ETW since they came out (but not continuously!!!)
first crash I've had that totally stopped the prog.

Sound driver causing crashes?

The only thing that I have read about sound drivers are (1) Only have one sound device loaded-whether onboard or Sound Blaster for one, (2) update those drivers, (3) set the sound channels to 64 or 128, and (4) set the sound cache to 300mb.

cheers irishron.

have only 1 sound device (on-board and ATI vid card sound devices disabled.)
have latest (year old!) drivers
sound channels set to 128
have increased sound cache to 300MB from 100MB

will have another go at the battle later.
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update - replayed battle with new size sound cache - battle played fine - still lost it though