Hopefully a couple save/edit cycles will fix the problem. If not, or you feel tempted to try some hex editing anyway;
In Hackman 7.0x you would open the data.000 file and search (ASCII mode) for 'AgentsV'. The 'A' will be selected when the program moves to that part of the file.
To move forward in the file by the given offset, select the menu 'Edit | Goto...' (or hit Ctrl+G), fill in the offset (6A5 in this case), in the Settings section select 'From this position', leave the Mode on Hex and hit the 'Goto...' button. The program will then jump forward to the start of the first resistance value.
Since you have negative 30 resistance, you should see something like 'E2 FF FF FF' repeated 4 times, forming a complete 'row', though probably looped around from where it starts to finish on the next line (the first 'E2' should be selected when you jump forward in the file; from there you would just click on that E2 to make sure the hex column has focus, and then start typing to overwrite the existing values). You would change that full 'row' (16 bytes) to all zeroes to get back to a base resistance value of zero; for a Magic Barrier level 3 resistance boost of 15, you would edit the four values to read '00 00 00 0F 00 00 00 0F 00 00 00 0F 00 00 00 0F'.
There was a serious filesize limit introduced in the freeware version of Hackman 8.x (it will only open the first 200KB of a file, or something like that). Here is a working link to the previous version of
Hackman (7.02) (click on the largish blue button with the down arrow, then again on the next page). Other hex editors should pretty much have the same features, at least as far as basic search and editing is concerned.
