This has been an issue we've been trying to find a solution to for some time. The problem is that only about 4 users (including you) have contacted us about it and many haven't had the time to help figure out why this is happening or simply haven't responded.
Newt requires at minimum read/write access to the ADMIN$ share (\\PCName\ADMIN$), but it also requires the ability to remotely start & stop services. In 99% of cases, if one as administrator (ADMIN$) access, they also have rights to remotely control services. It's only in this particular case with roughly 4 users where we've seen an inconsistency. In reality, this is a Microsoft security issue, except that it affects Newt and other remote administration software like ours. We're not sure if this is a bug in Windows 2008 Server or if it's intentional, but we're willing to work with you as long as it takes to find a solution to this issue.
Are you 100% sure that both of these accounts have the same exact rights? If so, I'm leaning more toward a bug in Windows 2008 itself.