I still haven't been able to determine what causes this strange behavior, but I have been able to correct the issue when it happens by checking for chr(255) in the field and then programmatically pressing the windows key twice for the user.

IF this.value = CHR(255)
	#DEFINE VK_LWIN                 0x5B           
	#DEFINE VK_RWIN                 0x5C
	#DEFINE KEYEVENTF_KEYUP         0x2

	DECLARE keybd_event IN Win32API ;
  		SHORT bVk, SHORT bScan, INTEGER dwFlags, INTEGER deExtraInfo
	keybd_event(VK_LWIN,0x5B,0,0)
	keybd_event(VK_LWIN,0x5B,KEYEVENTF_KEYUP,0)
	=INKEY(.3)  && Thanks to Sergey once again
	keybd_event(VK_LWIN,0x5B,0,0)
	keybd_event(VK_LWIN,0x5B,KEYEVENTF_KEYUP,0)
	CLEAR DLLS keybd_event
	this.value = " "
	WAIT WINDOW "Please enter the payment method again." NOWAIT
	RETURN 0
ENDIF