When you use Internet Explorer 5.0/5.01 to connect using a Secure Sockets Layer (SSL) session, the SSL session is renegotiated every two minutes.
You are probably unaware of these occurances, unless you are using basic authentication over the SSL connection.
The problem is caused by the default SSL cache time-out of two minutes, and uses the shortest value on the client or server.
You can alter the SSL cache time-out by using Regedt32 to navigate to:
On the Edit menu, Add Value name ClientCacheTime as a REG_DWORD data type. Using the Decimal Radix, set the data value in milliseconds. The two minute default would be 120000. A data value of 0 disables secure connection caching.