Since you bought your mini with OS X already on it vs having installed it yourself odds are that the install is a bit old, especially since it doesn't have 10.6.2 on it. At some point, and I'm guessing it was after your mini was setup, someone discovered a way to get much more constant booting with practically no hanging. The latest NBI 0.8.3 RC4 has the fix and it can be done manually also. It involved adding a key and value to the com.apple.Boot.plist in the /Extra directory. You might want to look into finding it here in these forums and adding that change to your machine.
Mini1: Vostro A90, Black, 2G, 1.3 Webcam, Bluetooth, 64G SuperTalent, OS X 10.6.4
Mini2: Mini9, Black, 2G, 0.3 Webcam, Bluetooth, 32G RunCore, OS X/Win 7, internal PCI-e SHDC Reader
Mini3: Mini10v. Black, 2G, Webcam, 640G HD, OS X 10.5.8/Win 7/Ubuntu [Hibernate w/NBI 0.8.3 RC4] Dropbox Referral