Those are the available write speeds with your burner/firmware/media combination. Since the verify was OK the disc should work. You could try with Taiyo Yuden CD-Rs too.
Try burning at 4x or 6x since those blanks are rated for 8x burning after all. You could also clean your burner using a lens cleaning disc, or even manually if you know how to do it.
Right-click ImgBurn's shortcut and select Run as Administrator. Does it work OK when you do that?
Alternatively you could try using another I/O interface (you can change it in Tools -> Settings -> I/O tab).
You should've left Verify enabled as that what tells you if the burn was good or not. You can still use the Verify mode to check that disc against the ISO image.
If verify is OK then you should read this -> http://forum.imgburn.com/index.php?showtopic=12200
Have you tried with another disc from that spindle? How about a disc from another spindle? Also try with the 8x rated (MKM-003-00 dye) Verbatim blanks.
Wouldn't make a difference since ImgBurn doesn't install anything on your system: it just extracts the ImgBurn executable files in its folder under Program Files ("Program Files (x86)" if you're using a x64 OS).
Have you looked for the latest drivers for your motherboard's chipset and/or storage controllers as advised above? Use SIW to identify them. That would help with the system stability issue as well.
(unrelated to your delay problem)
There's newer firmware available for your burner (remove any disc and close the tray before updating then reboot after it's finished).
Try burning at 4x. Try cleaning the drive with a lens cleaning disc, or manually if you know how to do it.
If all that doesn't help then read this: http://forum.imgburn.com/index.php?showtopic=8000
Why would LUK want to do that when there are plenty of solutions? e.g. Daemon Tools, Alcohol 52%, Virtual CloneDrive as you mentioned, etc, all of them freeware.