I have suspected that the Blank entry in the MSCONFIG Startup list was due to an incomplete cleanup by an un-installer.. or a failed attempt from from an installer

Haveing seen this in win 9x and winXP boxes it certainly isnt specific to any one MS OS.

We cant blame any of the anti-spyware tools on their own, as I have seen it in machines that didnt have these installed. But boy is it easy to blame Spyware, every machine where I have seen this Blank entry has had spyware to remove. I suspect it is possable to duplicate this by useing some of the anti-spyware tools in a remote mode (Bart PE)..

As the registry is a large text document it only takes the insertion or non-removal of one character (like the CR in a normal Doc) for it to show a blank entry.. and in some areas cause a nice selection of probs.

Summery:
It is very safe to remove the entry from the startup list.
if your uncertain.. do your scans again and be sure that you do so in SAFE MODE.. run one of the other memebers of the holy trinity. (Adaware, Spybot SnD), DO a scan with either TDS or The Cleaner (and do this in safe mode)