(bad Crc)?

bitdark

I have recently noticed this when I am observing the scanning of my copy of BitDefender AV 2009. It happens that the antivirus scan engine was stuck at a file, which ended as "(BAD CRC)". Before I can take it down the file has finished scanning & the particular path disappeared.

I would like to ask what is going on with the particular file path that ended with the phrase as stated above. I've heard that it indicates a corrupt file, but it seems it only occurs on .zip files. May I ask what exactly is the problem, & why is BitDefender showing this kind of things on my system.

Just to note I've just replaced my hard drive when my old one got broken. I've just completed setting up the system & did a quick scan with BitDefender (with no viruses whatsoever). It appears the message only appears when I'm performing a full or deep system scan.

On the side note, I would like to ask if it is normal for the scan engine to go beyond 4 hours of scanning. I have a 80GB hard drive with 2 external ones, 1 80GB & 1 250GB, the latter which have only a few files. As I've noticed the scan seemed to be stuck in the C drive for 3+ hours before scanning the external drives. Have recently installed a 2 GB RAM with an already-installed 1 GB, & the RAM type is DDR2 5300 SODIMM.

Any help would be appreciated.

alexcrist

Hello,

Bad CRC means that that particular ZIP archive is corrupted, and the files archived in it cannot be extracted correctly, thus resulting in an incomplete or corrupt file.

This error doesn't appear to you on quick scans because, by default, Quick Scan doesn't scan archived files, so when it reaches a ZIP file (or any other archive type), it doesn't try to unpack the files. It just scans the archive, as a simple file, and moves on.

The scanning time depends on a lot of factors, such as:

- scan settings

- scanned file types (if, for instance, you scan many archives or packed files, a lot of CPU time will be taken by unpacking/unarchiving the content of those files).

- other applications running in the system, that might take CPU time and/or that might be monitoring system activity (such as other security or logging applications, or resource intensive applications)

- storage device (the reading speed of the HDD/CD/whatever device you're scanning)

Also, in case of read errors, the same file is attempted to be read a few more times. For instance, if the HDD has a read error (caused by whatever reason), it will attempt to read the file again, before deciding to give up and say "read error".

Also, in case of corrupted archives (such as in your case), unpacking those files takes a longer time than usual, because different algorithms are used to try to recover/reconstruct the lost data.

Basically, there are too many factors and I cannot say if the time it took to make a scan of your system is normal or not.

Cris.

bitdark

Thanks. I'm asking this because I find that after adding more RAM, replacing the hard drive, & recovering the system to the latest system recovery CD I have, it doesn't seem normal for the hard drive to hang around the C drive for longer than it used to be (before when I used my old hard drive the scanning time for the C drive is usually 1 1/2 hours.

Thanks for the reply. Of course, if there's a way to fix or get rid of this problems I would be glad to hear. For now I think I'm going to use a chkdsk scan to see what can be done.

alexcrist

Just watch the scan, and see at what files the scan stops for too long. Also, watch for those Bad CRC messages, and manually check those archives for integrity (try to unzip the files, to see if they can be extracted correctly).

Cris.