Comodo AV appears to detect a false positive.
Product: Apple QuickTime 7.6.9 (1680.9 en-US)
Product Link: QuickTime Player User Guide for Mac - Apple Support
Detected File: C:\Program Files (x86)\QuickTime\QTSystem\QuickTimeUpdateHelper.exe
File SHA1: 54f0ee528eaa0f33d393fe8a3d329c20d7021b2d
Name of Detection: Heur.Suspicious
CIS Database Version: 7059 (2010.12.14)
According to VirusTotal, Comodo is the only one crying wolf:
http://www.virustotal.com/file-scan/report.html?id=ab18b11daa497b13d83f2899ab423ddaa1aa852676b24b4484f91c8add59a251-1292337491