Thumb Drive issues

I have two usb drives one that I just bought that is HP 16 Gb and another one Kingston 4 GB. The Kingston once has the write protected error pop up a lot more frequently since I copied alot of stuff from the drive. I tried my new usb drive right after the Kingston one and it showed up temporarily until I tried copying a lot of stuff to the flash drive and it then said the drive not found(can't remember what it said exactly). I suspect the write protected flash drive did something to make the E:drive unusable for other drives using the letter E. I though this problem was the new thumb drive was no good because I plugged the drive in an old computer and the same thing happened(device hardware installs but properties show 0 bytes used 0 Bytes free . What really matters is I am also working on my mom's computer fixing it from viruses so I have used the Kingston write-protected one a few days and then tried a good drive last night and discovered the problem on her computer also. Now I have three computers to fix. I changed thumb drive letter from E: to G: and now that one shows up again normally. So I fixed the problem for the flash drives not showing up. The only thing is my mom uses alot of drives for scrapbooking and I was wondering if it is possible to get drive E:working normally again(most of them use letter E: and changing drive letter would be a bit too much trouble)) Would a USB cache flush work in order to make E work again(write protected drive is the only one that works and shows up in E: correctly) Need some help and advice! Thank you

 

Where did you buy these flash drives? It sounds like the behavior of those Chinese knock-off counterfeit drives that never work properly.

 

Well actually my drives are good until I used the Kingston. Every good usb drive that gets plugged into the computer wouldn't show.I semi figured out how to clear the USB cache so that my flash drives are recognized when plugged in(without HP and Kingston drives) except when I have the HP one plugged in(and it works) the other flash drives plugged in afterwards won't show up.I feel so frustrated that I have to fix this problem on three computers. I need the flash drive in its perfect state(I have formatted it several times but like I said flash drives plugged in afterwards don't show up)

 

oh and both the Kingston and HP work at the same time no matter what the order, I have to flush USB cache between switching the order I put them in.