Problem getting posted data

[Harald]

Hi,
we have an ASP to receive soap messages as follows:

....
Set doc = Server.CreateObject("MSXML2.DOMDocument")
doc.load(Request)

if Len(doc.xml) = 0 then
ErrorMessage(...)
exit sub
end if
....

The problem occured by moving from W2K / IIS 5 to W2K3 / IIS6: When posting
a soap message larger then about 500 KB, Len(doc.xml) returns 0!! So we are
not able to transfer larger Soap messages. The same code works for W2K / IIS
5 even with sizes over 6MB! The doc.load() function returns rather quickly
without any errror (we have tried by inserting an error handler) but
obviously the DOM tree is not built. Btw: we have also tried
MSXML2.DOMDocument.4.0. We use MSXML4 SP2.

Q: Any idea of limitations, for example for POSTs or ASPs?
Q: Any known properties to set for solving the problem?
Q: Any known limitations for MSXML4?

Thanks a lot for your help!
- Harald