[plt-scheme] dns-find-nameserver complains "input in flex scanner failed" (but works anyway)

Hi. New to Scheme as of couple months ago. Coming from 25 years of C,
C++, mostly in commercial development but not actively last 5 years or
so. Recently Paul Graham's stuff caught my eye, plus heard some
Clozure hype. Drove home to me I'd managed to avoid ever learning
LISP. Looked at Common Lisp but found it too baroque and fugly.

Enjoying the mind warp so far. Without a language/library/IDE as
comprehensive as PLT scheme, I doubt I would have stuck it out this
long. I'm really impressed. PLT Scheme seems like a nice balance/combo
of Scheme's elegance and CL's utility (at least that's my naive first
impression).

Tiny bug report:

With DrScheme, version 4.2.3 [3m], Language: Module.

 (require net/dns)
 (dns-find-nameserver)

Gives the output:

"input in flex scanner failed" (red italics)
<blank line>
"d.d.d.d" (a valid IP address for the name server)

In other words it gives this error message, but dns-find-nameserver
and the other net/dns functions that a nameserver seem to work fine
anyway.

This is on Windows 7 64 bit. No such error message on OSX 10.6.

What feels like a dumb question:

What exactly is this red italic text? It doesn't seem to be from
(error) because execution continues past it. It doesn't seem to be an
exception because I tried catching it. What is it?

Thanks,
Greg