Increasing number of Workers for Standard Manager

Hi;

I have a problem:

Plattform = Windows Server 2003 32-Bit

EBS = 11.5.10.2 RUP 6

We have tried to increase the number of Workers of Standard Manager from 20 to 30, the extra processes started well, but when we were testing after reached 15 Concurrent Request running together the other processes(16-20) completed with error.

" Program exited with status 128

Cause: The program terminated, returning status code 128.

Action: Check your installation manual for the meaning of this code on this operating system.
APP-FND-01630: Cannot open file F:\OracleEBS\ebsprodcomn\temp\OF2B7.tmp for reading

Cause: USDINS encountered an error when attempting to open file F:\OracleEBS\ebsprodcomn\temp\OF2B7.tmp for reading.