Posting Large Dataset causes 404 Error from WebService

I've noticed plenty of posts on Http errors related to upload size but none of the solutions seem to work for me. I've got a web service that accepts a dataset over http, and if the data being uploaded is small like just a couple of rows, it works just fine, but when the amount of data is quite a lot (a couple of MB), I get a strange 404 error. I checked the event log and got found this Web Event warning description:

Request format is unrecognized for URL unexpectedly ending /MyService.asmx

This is a post operation, and though I'm yet to try with the dataset exported to xml, I'm just curious as to why this wouldn't work even when I'm debugging on the same pc hosting both iis and sql. And what would possibly cause it to work for small datasets and not large ones? I've increased the asp upload limit to like 2gb but still no joy.

Anyone got any ideas?

Oh, I'm on win7, IIs7, Asp.Net 3.5, vs2008, Sql2008 and an awesome Ghostbusters mouse m开发者_JS百科at. :D

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Solution found: Setting httpRuntime maxreqlength and timeout to prevent the web service from timing out.