In addition to the previously mentioned solutions:
1) Excel Not Installed proper server… AppServer (Online PeopleCode) or ProcSched (Batch / AppEngine PeopleCode)
2) Wrong version of Excel (64 bit vs 32 bit)
We found a 3rd issue
3) Tuxedo and Oracle Proc Mgr services started with VM user ID instead of local system user ID (PS Admin / Infrastructure issue).
Hope this helps.