I inserted a blank disc to format it, but the drive does not recognize it. Or I formatted the disc, but InstantBurn 5 won't mount it.

If the disc is still not recognized after you launch InstantBurn 5, you may have third-party drivers installed in your PC. Insert the disc in the drive, right click on the drive icon in My Computer and select !‥Properties!‥ from the contextual menu. If any UDF file format (i.e.: "UDF1.02", "UDF1.5",  "UDF2.0", "UDF2.01", "UDF2.50" or "UDF2.60") appears as the file system, then the disc is mounted using InstantBurn. If not, the third-party software is conflicting with InstantBurn.

If you have used third-party packet-writing software on your computer, then some files, such as UDF reader files, from this software may still be in your system. If these files have control of the CD/DVD drive before InstantBurn, then they are prohibiting you from using InstantBurn.