No buffer space available max connections reached?)

Can anyone help me with this error message please?  "No buffer space available (max connections reached?)"

 

Dell Vostro 1500 (originally running XP SP3) now running W7 Home Premium 64 bit Build 7600

Dell Vostro A90 (originally running XP SP3) now running W7 Home Premium 32 bit Build 7600

Dell Vostro 1520 (originally running Vista, then W7 RC1 64 bit Build 7100) now running W7 Ultimate 64 bit Build 7600

Dell Inspiron 1521 running XP SP3 without any problems

 

Using financial websites, in the City of London, I normally run three Java graphs on each machine.  No problem was ever observed with Windows XP, Vista or W7 RC1 Build 7100.  These graphs update continuously, at around 15 second intervals.

 

Since updating these computers to Windows 7 the 1500, A90 and 1520 all exhibit the same problems while using either Firefox or IE8 as the browser.  The Java version was 6.17 and is now 6.18.

 

After some three hours each graph shows “Error 1 no buffer space available (max connections reached?) : Connect”.  At this point the browser cannot connect to any web site.

 

I have tested with all browser add-ons disabled, no other utilities running, even running without firewall.

 

What has happened to the ability to set files and buffers that existed in DOS or boot.ini?

 

Microsoft have been unable to give me an answer from 1st November till now (30th January)

 

Thanks for any pointers you can give me.