PUM.Hijack.StartMenu

I have just run a malawarebytes quick scan and the log is as follows

Malwarebytes Anti-Malware 1.65.0.1400
www.malwarebytes.org

Database version: v2012.10.08.07

Windows XP Service Pack 3 x86 NTFS
Internet Explorer 8.0.6001.18702
Baz :: BAZ-DESKTOP [administrator]

08/10/2012 18:41:24
mbam-log-2012-10-08 (18-54-15).txt

Scan type: Quick scan
Scan options enabled: Memory | Startup | Registry | File System | Heuristics/Extra | Heuristics/Shuriken | PUP | PUM
Scan options disabled: P2P
Objects scanned: 220800
Time elapsed: 8 minute(s),

Memory Processes Detected: 0
(No malicious items detected)

Memory Modules Detected: 0
(No malicious items detected)

Registry Keys Detected: 0
(No malicious items detected)

Registry Values Detected: 0
(No malicious items detected)

Registry Data Items Detected: 1
HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced|Start_ShowMyComputer (PUM.Hijack.StartMenu) → Bad: (0) Good: (1) → No action taken.

Folders Detected: 0
(No malicious items detected)

Files Detected: 0
(No malicious items detected)

(end)

When I run deep scans on Avast nothing is showing, what does this mean?

it is not a infection…but a setting

PUM = Possible Unwanted Modification

so who did the change, you or was it malware… MBAM does not know