Autohotkey input random alphanumeric characters and halted suddenly

[lennyli]

Hi, we created a script that has the below instruction for the first part:

Run, C:\Program Files\FTR\ForTheRecord\TheRecordPlayer.exe
Sleep, 2000
Sleep, 2000
send,{tab 11}{space} ;click file open button
Sleep, 1000
send,{tab 6}{space} ;click the other button in file dialog
WinWaitActive, Open other...
send,D:\10.33.98.70\Audio\public\20170509\HC-18
Sleep, 1000
send, {enter}
Sleep, 1000
send, +{tab} ;shift tab
Sleep, 1000
send, ^a ;press control a to select all
send, {enter}
send, {tab 24} ;24 tab to goto start of time
send, 094120 ;start time
send, {tab 2}
send, 094202 ;end time
send, {tab 5}{space} ;click save button
WinWaitActive, Save Copy To
send, !f ;send Alt F
send, D:\10.33.98.131\DARTSaudio\2017\HCB1745-17
send, {enter}
Sleep, 2000 ;wait 2 secs to Not to click cancel button
WinWaitActive, TheRecord Player
send, {enter} ;click the successfuly saved OK button on TheRecord Player dialog box


The above repeats itself with different values
What we dont understand is that after looping the same steps many times, the running script halted and inputed some random alphanumeric characters into one of the file open dialog box. Do you know what could have caused the script to fail 2 hours running about halfway into the codes?

[lennyli]

In recent tests, we didn't see the script input a long bunch of random characters anymore, but our .ahk instruction file has typically 7000 lines of instructions that repeat similar key strokes but inputting different numerical values to the software we launched. Even without touching the computer or seeing any error messages, the script would suddenly stop running halfway in the middle, so we have to edit the .ahk file to make it run the rest of the instructions.
Does anybody have a clue why autohotkey would suddenly stop like this? is it because with heavy loading the autohotkey is too overwhelmed?