I have a PIX 525 6.3 that has all interfaces configured and MTU set to 1500 bytes.
I am experiencing fragmentation issues.
I have LAN workstations that cannot ping anything connected to the PIX outside interface and beyond with packets larger than 992 bytes.
I can ping servers on the DMZ interfaces with 1472 bytes just fine.
The Internet edge router and devices directly connected to the PIX outside Interface, only the 992 bytes. So it is not an Internet fragmentation issue and there is no VPN in play.