I have been having this happen more lately as well. I am on an Intel Mac Pro 2.66 GHz with  2GB RAM and running 10.4.10. I am still running parallels version 2.5 (recently upgraded to 3214). I use Parallels to design UI for ASP.Net web sites and have been having more trouble lately when testing sites in multiple browsers. I usually have Firefox and IE6 open for testing while developing in Visual Studio 2005 and IIS as the web server. 
Where do I find the crash logs and what, specifically, should I be looking for there?
EDIT:
Here is what I see when looking in the Console app under CrashReporter for Parallels.crash.log:
Date/Time:      2007-08-15 09:24:07.784 -0500
OS Version:     10.4.10 (Build 8R2218)
Report Version: 4
Command: Parallels
Path:    /Applications/Parallels/Parallels Desktop.app/Contents/MacOS/Parallels
Parent:  WindowServer [67]
Version: 2.5 (2.5 Build 3214.0)
PID:    275
Thread: 16
Exception:  EXC_BAD_ACCESS (0x0001)
Codes:      KERN_INVALID_ADDRESS (0x0001) at 0x01c68000
					 
				
			
			
			
		 
		
		
		
			
			
				Last edited: Aug 15, 2007