dorkus,
This error is not caused directly by AVAST. It is usually indicative of a problem within the Windows Kernel Stack Dump.
TXLDERR_BOOTSTRAP /Error 193 0xC1... unable to bootstrap KERNEL is another form of the error message.
The 0xC error messages indicate that a kernel-mode process or driver incorrectly attempted to perform a memory operation. This error message is typically caused by a faulty device driver or software.
You can try searching the Microsoft Knowledge Database for "fixes". Microsoft has a downloadable Debugger utility, but unless you are very confident in using such tools, then you may want to try going back to a "restore point", or doing a partial reformat of Windows.
I will do some more research as there can be many causes for the error.
You can try to isolate the "offender" by using MSCONFIG to shut down a few programs at a time to see if you can get Avast to load and run properly. If you can isolate the cause, then we can fix it easily. (I hope.
)
Until I get back to you, do the simple preventive measures:
Diskscan with "repair errors on disk automatically" set and
Defrag the hard dirve.
techie