I have just installed the latest update.  I copied my file to another location, downloaded the complete update and unzipped it.
 
I can open DBA, and I can get into the Sales Order screens, but when I try to get into mfg or Items, I get this message:  A record was not found in FILELOC for file - ISSRINV.B  -4, then I get ISSRINVL.B  -4.  They I get this error message and can't get out of it without control/alt/deleting myself out.  An error message was not found in ERRMSG.B file 405.
 
Can anyone help me please.

Have you figured out which step it is?  I'm having the exact same problem.
 
Here's a list of some of the things going on.  Maybe someone can see what I missed.
 
 
WO-A:  
A record was not found in FILELOC for file - ISWODESC.B - 4
The field you are trying to use is unallocated.  It may belong to a file that hasn't been opened yet, or was an array that was removed from memory - BK.DESC.NUM
 
IN-A:
A record was not found in FILELOC for file - ISSRINV.B - 4
A record was not found in FILELOC for file - ISSRINVL.B - 4
 
SO-J:
A record was not found in FILELOC for file - BKARRDSC.B - 4
 
SR-A:
A record was not found in FILELOC for file - ISSRDESC.B - 4
A record was not found in FILELOC for file - ISSRINVL.B - 4
A record was not found in FILELOC for file - ISSRINV.B - 4
An error message record was not found in the ERRMSG.B file. 405
 

I followed the instructions and did the ISUPDATE and then UPDFILE.  The results are always the same.  Is there a step missing from the instructions?

I'm slowly going insane trying to figure out what I did to fix this.