GNU Emacs 21.1.1 prepends drive letter to source pathname in gdb mode

[Starwatcher]

I am a happy user of the windows build of Emacs: "GNU Emacs 21.1.1
(i386-msvc-windows98.3000)" EXCEPT that it does not seem to integrate
smoothly with Cygwin gdb.

The problem I have is that, when using gdb-mode (M-x gdb), the automatic
"source buffer" doesn't display the source code although I can see the
instruction pointer marker in the left margin and the right source file
basename (e.g. "hello.c") in the status bar.

The reason seems to be Emacs failing to load the source file because
both Emacs and Cygwin gdb have prepended the drive letter to the
pathname of the source being debugged, resulting in an invalid pathname:
            <driveletter>:/cygdrive/<driveletter>/<unix-like
pathname>/filename.c
e.g.:
            e:/cygdrive/e/dev/hello/src/hello.c

Any idea to work around this ? (through Emacs configuration, gdb
options, gcc compiler options, etc.)

PS: I suspect the version of emacs delivered with Cygwin does not have
the problem but, for several reasons, I don't want to go through the
hassle of using/configuring Cygwin Emacs...
--
Laurent