Not the PC is junk attitude. This is what is wrong with the world!
Here is the deal, I fully agree that trying to run all of this on a MAC even with the Windows emulation is not a wise idea. I have about 15 computers, 1 is a MAC that was an old customer machine that the hard drive died in it. I only use it to talk my MAC customers through screen by screen if I do not use my PC and LogMeIn to control their Mac.
Anyway, here is the deal, your whining about slow and infested PC's will not solve your problem. Slow PC's are usually due to the Market place selling garbage for low prices that should never have been sold. Underpowered processors and not enough RAM. Top this off with allowing kids to use a PC as a online gaming machine for free games. Nothing in the world is free. Also the MAC mindset is everytime a new computer comes out, you must go buy it, you would be surprised how many 4-10 year old Windows machines I see on a DAILY basis. Computer life cycle at tops is 4 years if you want to stay reasonable current.
A Windows machine that needs an enema is usually due to the operator not using the machine wisely. I deal with this every day, I make a lot of money solving these issues. My teenagers have never killed or screwed up their Windows machines and I have never spent much time training them. They are just street/computer/Internet smart and do not do foolish things.
Anyway enough of this and back to your problem.
Search the forum for more info on the MAC and SD card problems, you are not the first here.
Anytime you plug the x36HP scanners in to a USB connection, it should prompt you for Serial or Mass Storage. You use the Yes/No 4/6 key to choose. Serial mode is for remote controlling the scanner or charging the scanner when it is turned off. Mass Storage is really the SD card, this would have been a better description.
Unclear if your SD card is corrupt, likely so??? If this is the case, you will most likely need to remove the SD card and format if you do not have luck with running Sentinel on your other SLOW Windows machine, that will likely work just fine!