going mental - autorecovery system

I have beentrying to think of a way to do this for ages and am slowly going mad.

I have a filtering engine that scans the entered message for disallowed words. THe filter can be enabled or disabled and its state is recorded internally in a variable scannerStatus as either 0 or 1. For error handling i want to include an auto-recover should this variable become corrupt (as the scanner will have an unkown state) as this is network software security and error systems are paramount.

I can detect if the scannerStatus has an errounous value - but if it does i want to auto-correct it to the last state, so i need to record the state as it changes, if i simply copy it - the copy will become corrupt as well as the original - so thats no help. is tere a way of 'locking' a variable and then 'unlocking' when i wish to access it. Storing it in a text file seems a little ineffcient and it is possible it may become overwritten with corrupt value.

tVMia

use three variables: inputchange, current status, and backup

every time inputchanged is used, first check it to make sure it is not corrupt. Then, set backup equal to current status. Then, set current status equal to inputchange. You can check as often as you want if currentstatus is corrupt and if it is, you can set it equal to backup. To make it even less hackable, you can even backup your backup variable and with the same value that is in it, but under a different name. Good Luck.