Tip of the Day: TechTool System Analyze error reports

Last week, we reported that the System Analyze feature of TechTool falsely reported problems with the System file - when checking the file on the newest Mac models (such as the 3400 and 7300). Based on subsequent email I have received, there seems to be some confusion about the function of the System Analyze feature. Let me try to clarify:

a. System Analyze checks the System file for possible corruption. If it reports a damaged file it is a potential signal that you should replace the System file.

It accomplishes its check by comparing your System file's resources against a database of expected resources contained in the TechTool application (TechTool Pro has a similar feature that depends on its DNA file). If expected resources are missing or if unexpected resources are found (or perhaps even if certain resources are modified), a damaged file is reported.

Unfortunately, TechTool can not anticipate every legitimate change to the System file that may occur. Avariety of utilities modify the System file as a normal aspect of how they work. When TechTool checks this System file, it may falsely report it as "damaged."

Even more common, when Apple updates its System Software, it almost always makes changes that require TechTool to come out with a new version in order to avoid false error reports. This is almost certainly what is going on in these most recent reports of problems. That is, the software on the new machines has modifications that TechTool does not yet recognize.

b. Several readers have written that after getting a damage report from TechTool, they check the disk with Norton Utilities - and that Norton reports no problems found. They view this as a contradiction of sorts. It is not! Even assuming that TechTool's error report is valid (that is, not a false error as described in part a), Norton Utilities will likely not report a problem. This is because Norton is not checking for the type of damage that TechTool picks up. TechTool reports when something unexpected is found in your System file. Norton is more geared toward finding Directory damage and damaged media. It also checks for some more minor file problems (such as incorrect bundle bit settings).

Bottom line: If TechTool reports damage and you have no reason to believe it is a false report, and you are having problems that you cannot otherwise explain, replacing your System file is a good idea. A positive report from Norton Utilities has no direct bearing on this.