VS 2008 - SendKeys Not Working The Same On Every Computer

VB 2008 Express. I write a program designed for interacting with an Android phone that is hooked up to a Windows machine. One of the tools in my program is a utility designed to assist the user root their phone. Now in order to root it goes through a command line utility called adb which lets you access a terminal on the phone. It must then type commands in that terminal. Most processes that this program does can be done through a batch file, however rooting the phone isn't one of them. The reason being once it actually logs in to the phone's shell, it stops running commands because it just gets stuck on that line, waiting for it to finish.

So despite being a little primitive I designed that part of my application to use sendkeys. So the way it should work is:
1) It launches powershell as an administrator
2) Types the following commands (I have abbreviated the number of commands it types for the sake of this board. There's actually about 20 lines total):

SendKeys.SendWait("mount -o remount,rw -t yaffs2 /dev/block/mtdblock3 /system{ENTER}")
SendKeys.SendWait("cat /system/bin/sh > /system/bin/su{ENTER}")
SendKeys.SendWait("chmod 4755 /system/bin/su{ENTER}")
SendKeys.SendWait("flash_image recovery /sdcard/recovery-RA-heroc-v1.2.3.img{ENTER}")

Now it seems that for 90% of users, this works perfectly fine. However for a small group of people, this is what actually gets typed in to the powershell window:
> /system/bin/su{ENTER}
_image recovery /sdcard/recovery-RA-heroc-v1.2.3.img{ENTER}

For the people that have this happen to them, it's always the exact same thing. It's like it completely skips all letters until it gets to a special character. I have no clue what could be causing this. The only thing I have found was that sendkeys wasn't totally supported but that running it as administrator would fix that, which is why I now have it run as admin. But that didn't work. I also had some success by using powershell instead of cmd, but it's still failing for a small number of people.

Every other part of the program works perfect except for this. I haven't found any common element between the people that it is failing on. They aren't running the same anti-virus or the same programs. I program and debug on Windows 7 64 bit, yet someone else can run it on the same OS and it won't type it out properly. Is there something better that I could be using instead of sendkeys?