"Access is denied (0x5)"

I am running 2 PCs - 1 is running fine, the other is getting lots of errors. Any idea why?

Sample 1:
4.45
Access is denied. (0x5) - exit code 5 (0x5)

Resuming computation at 169/14847/17547
Resuming computation at 169/14847/19077
Resuming computation at 946/83607/85677
Resuming computation at 1267/109797/110067
Resuming computation at 1267/109797/113577
Resuming computation at 1450/125096/125636
Resuming computation at 1450/125096/129056
Resuming computation at 2397/206815/211765
Failed to open checkpoint-file for writing. Exiting.

Sample 2:
core_client_version>4.45
Access is denied. (0x5) - exit code 5 (0x5)

Resuming computation at 345/37620/43290
Resuming computation at 345/37620/43290
Resuming computation at 1119/103230/104940
Resuming computation at 1471/121680/121770
Resuming computation at 1471/121680/125280
Resuming computation at 1654/133380/134100
Resuming computation at 1654/133380/134370
Resuming computation at 2587/195209/198719
Failed to open checkpoint-file for writing. Exiting.

Sample 3:
4.45
- exit code -1073741819 (0xc0000005)

Resuming computation at 26058/1193586/1195544
Failed to open checkpoint-file for writing. Exiting.