Errors 2,3,5,18,100,101,151,152,154,156,157,158 are usually associated to problems with the PC hard disk (verify the hard disk with scandisk utility or similar program) - or possibly a defective floppy/floppy drive when backing up/restoring or installing the software.
Errors 5 and 150 is also associated with backing up to a write protected floppy disk or trying to install the software from a diskette which contains hidden system files (formatting the diskette before copying the installation files to the floppy usually fixes that problem).
1: Invalid function number
2: File not found
3: Path not found
4: Too many open files
5: File access denied
6: Invalid file handle
8: Not enough memory
10: Invalid environment
11: Invalid format
12: Invalid file access code
15: Invalid drive number
16: Cannot remove current directory
17: Cannot rename across drives
18: No more files
100: Disk read error
101: Disk write error
102: File not assigned
103: File not open
104: File not open for input
105: File not open for output
106: Invalid numeric format
150: Disk is write-protected
151: Bad drive request struct length
152: Drive not ready
154: CRC error in data
156: Disk seek error
157: Unknown media type
158: Sector Not Found
159: Printer out of paper
160: Device write fault
161: Device read fault
162: Hardware failure
200: Division by zero
201: Range check error
202: Stack overflow error
203: Heap overflow error
204: Invalid pointer operation
205: Floating point overflow
206: Floating point underflow
207: Invalid floating point operation