PROBLEM Error occurred while scanning MBR sector of the 3. physical disk. Error reading sector. Error occurred while scanning MBR sector of the 4. physical disk. Error reading sector. FORUM REFERENCES These threads mention the problem to varying degrees: MBR error MBR Error Solution Win 98SE NOD32 2.5 error message Strange problem... error message re memory? Error during scan New user in a hurry Memory not being scanned- Help? Scan error:Operating Memory using WIN98SE Problem running scan on USB Disk Question? MBR 2 sector error MBR3 Which USB device(s) might be causing the MBR3 error? USB 2.0 Drive G: USB Flash Drive (always plugged in) Drive H, I, J, K: USB Card Reader (each slot is a different drive, and the drives are only "available" when a card is inserted) Drive N: USB Hard Drive (not currently connected to the system, used only for backups, currently not shown in Explorer.) If it was any of the 4 card reader drives, wouldn't there be MORE errors, one for each drive? USB 1.0 Mustek 1200UB Scanner It can't be the printer because it's parallel, not USB. Camera is serial, not USB. No other USB devices. No firewire devices. MBR4 Would MBR 4 definitely be the page file? SYSTEM FACTS Platform: Windows XP Pro SP2. - DEP is enabled (OptOut), so exceptions can be made for programs with compatibility issues. No exceptions so far. Firewalls: - ZoneAlarm Pro 5.5.094.000 (It has a corrupt database, some ZAP features do not work properly, and it needs to be reinstalled...but not until I write down all the million custom settings first.) - The 2Wire aDSL modem-NAT/DHCP router-gateway has its own hardware firewall. This protects the entire network. - PeerGuardian 2.0 is being used as a firewall supplement. No file-sharing programs. Users: Multiple users. I am logged in as administrator and the only one logged in at present. Boot Sector Managers: None that I know of. What are some examples of boot manager programs, so I can tell for sure? Ad-Aware Pro's Ad-Watch? Spybot? MS Antispyware? Printers: The local printer is parallel port (LPT1), not USB or firewire, so that should not contribute to the errors. The network printer is the same brand and model, Lexmark Z42. Network: It is a home network, peer-to-peer, not client/server. All 4-5 PCs are wired through a hub. The router/gateway is also wired to the hub. NOD32 is installed on only this PC. Other PCs have different AV programs and operating systems. All are protected by the hardware firewall.