Hello Christiane,
Vista is in, what we call, a 'Mod-Auth' Tamper state. There are 2 types of Mod-Auth tampers.
1) A critical system file was modified On Disk - What this means is that the file, located on the hard drive, was modified in some way. This can be caused by a malicious program (spyware, malware, virus) or by manual file modification (by a user of the system).
2) A critical system file was modified In Memory - What this means is the file itself (on the hard drive) is un-modified, but the code, from that file, running in the system, was modified in some way. and is usually caused by a running program that is incompatible with Vista.
Because there are No Mismatched files listed under the "File Scan Data-->" line of your Diagnostic Report, your issue is a In Memory Mod-Auth and therefore caused by an incompatible program. This means there is a program install and Running that is trying to access parts of the OS that Vista does not allow which by definition means it is incompatible with Vista.
In addition to why a Tamper occurs, it's also important to understand how Vista detects the Tamper event. There is a Service that runs in Vista that detects a Tamper to a Critical System file. But this Service runs randomly, so if you were to install an incompatible program and run it, Vista (most likely) would not immediately enter a Tamper State and it could take some time for the Tamper to be detected. The important point to note is that the moment Vista detects the Tamper, you know that the program that caused the tamper, is currently running.
Below I have provided a number of steps to help you identify the program that is causing the tamper:
First, go to http://support.microsoft.com/kb/931699/ and confirm that you do not have any of the programs known to cause this type of issue.
Second, in your Diagnostic report above, you can see the line that starts with 'TTS Error:' followed by a bunch numbers: M:xxxxxxxxxxxxxxxxx- This is the Tamper Time Stamp and it breaks down like this:
(year) (month) (day) (time in 24format) (millisecond)
M:2008 05 20 1148 30442-
Now that you know the time of the tamper, you can now try to connect that time with a program.
1) Login to Vista and select the option that launches an Internet Browser
2) Type into the browser address bar: %windir%\system32\perfmon.msc and hit Enter
3) When asked if you want to Open or Save this file, select Open
4) In the left hand panel, click Reliability Monitor
5) Click on the “System Stability Chart” above the date 05/20
6) Below the chart, in the “System Stability Report” section look at the report titled "Software (Un)Installs for 05/20/2008"
7) Look for any program that shows "Application Install" in the 'Activity' column.
8) Since the process that detects Tampers runs randomly, it can take up to 3 days for the process to detect the tamper and set Vista to a Tamper State. Because of this, please repeat steps 5) thru 7) for the dates 05/19/2008, 05/18/2008 and 05/17/2008
This could tell you what programs were installed on or around the Tamper date and should help you narrow down the possible programs that could be causing the issue . Unfortunately, if you installed the program (say) on 09/01/2007, but you didn't run (and, hence, prompted the tamper state) till 05/20/2008, this process may not be helpful. The removal of any application you may have installed recently could go a long way to troubleshooting this issues as well since it may fall outside of the 3 day time frame described above.
Thank you,
Darin Smith
WGA Forum Manager
