The new wininet.dll which comes with Internet Explorer 7 uses new default timeouts:
INTERNET_OPTION_SEND_TIMEOUT- 30000 ms
INTERNET_OPTION_RECEIVE_TIMEOUT- 30000 ms
The good news is that you can now override these values by calling the InternetSetOption API (zero value seems to indicate infinite wait, see this example).
In previous versions, InternetSetOption didn’t work but at least the default values were quite large:
INTERNET_OPTION_SEND_TIMEOUT- 300000 ms
INTERNET_OPTION_RECEIVE_TIMEOUT- 3600000 ms