Hm- If there have been any changes in hardware/software or for that matter the brand of discs, this might be a reason for your sudden difficulty. It is possible that you will be unable to read the previously made (DLA) discs. Then again I have a rack full of CD-Rs made with it that read just fine. Ashampoo does NOT use packet writing programs and is truly transparent. I have burned both CD-R and RW along with DVD-R with no issues at all. In fact, I have been adding content to a CD-R with no problems.
You ask about "read only" on a CD-RW. This is not uncommon in my experience w/CD-RWs. You may get a message asking to "Erase" the disc before writing to it. I let the program do this since I use the discs for backup file storage updates.
Just Tested (7:45am) Ashampoo-It indeed will write to a CD-RW without 'erasing' it. It is a feature called "Update files..."
I will also suggest that you have Dell do a complete diagnostic rather than piecemeal. If you have a support agreement that includes on-site service-use it. If you have to ship the machine that is another matter.
Good luck and keep us informed.