I've debugged this a bit and determined that my problem was not originating from this particular condition, but from something else:

double d = pow(10,666);   // create INF
double n = 1.0;
double m = fabs(n-d);  // Panic

This causes USER-EXEC Panic with Reason number 3.

3 - This panic is raised when User::Abort() is called and the thread has no exception handler for exceptions of type EExcAbort.

doing just:

double m = fabs(d); doesn't cause the panic.

in MSVC/Win32, if I do this, originally d is: 1.#INF, (n-d) however is: -1.#INF.

In my application, I am comparing two doubles to a certain degree of precision, so what I do is

"if(fabs(a-b) < 0.00001)" and that pretty much dies when b is INF (resulting from a previous floating point operation).