>Only problem was that it didnt always work - I would run the program (say) 5 times in a row and the first 4 would work and then it would stop and cease. I wondered if this was because I was using beta code so was looking forward to having release version in (as of yesterday it is). I've rebuilt the MTDLL and regenerated the WDSL but at the GetMachineName call I constantly get

Are you running ISAPI or ASP listener? Did you try to simulate the same without going into the MTDLL? At first, I'd go with the lowest common denominator. If you always have it failed after 5 times, I'd run the Web Service as is first. Then, if the situation persists, I'd run it ISAPI, assuming you're ASP listener?