ISA not reflecting DHCP assigned IPs

Dear Friends,
I have a problem with our win 2003 SBS SP1. Its running ADS, SQL, Exchange and ISA.

ISA and DHCP do not seem to comunicate. I believe after the DHCP issues a new set of IPs, the should be picked by ISA.
Currently for the same computer, DHCP and ISA have different IPs. ISA IPs look static.

The DHCP also issues similar addresses i.e before and after the expiry of a lease period, a computer just retains its IP. I thought DHCP randomizes IPs.

I also have problems with browsers(winXp). On some computers, HTTPS sites do not completely load. It shows 'done' at the status bar but the pages are blank. There is no error report. Its the same for IE, Mozilla, Netscape, opera. I have waded through many articles but no success. I am tempted to completely format the affected PCs and reload afresh. But that is a big bomb!
Kindly assist.

The DHCP Client Static Packet filter only permits you to refresh the already assigned external IP address.

For example, when the DHCP lease has expired and the IP address on the external interface is lost or manually released, a renew of the IP address is blocked by the ISA Server Packet Filter module. The ISA service is not fully Plug and Play when the IP address is released on the external interface. Therefore, packet filtering is still applied to the interface.

A supported hotfix is available from Microsoft. This hotfix might receive additional testing. You must install ISA Server Service Pack 2 (SP1) before you install the following hotfix. To download Service Pack 2 for ISA Server 2000, visit the following Microsoft Web site: ISA Server 2000 Service Pack 2 (SP2)

Hotfix