most probably the interrupt is constantly getting triggered and interfering the running of enumeration sequence. Are these interrupts constantly being triggered? What is the code in the ISR of these interrupts? Have you tried tying the pins to a logic level so that the interrupt doesn't get tried, if so do you still see the issue?
There were no hardware issues on the interrupt firing, but the system worked fine once I added a seperate file "isr.c" with the interrupt handler "ISR_EXTR0". Is it necessary to add seperate file for interrupt handler. Earlier, I had added the interrupt service routine in slave.c file.
Please see http://www.cypress.com/?id=4&rID=27870.
INT0# is an 8051 interrupt and #pragma NOIV affects only the file in which it is mentioned. So, 8051 interrupts have to be placed in a separate file, without having #pragma NOIV statement.