I cannot back up any more files to cd rw It says it is read only. it has 45
million bytes on the disk and says no capacity left ..Is this disk really
full?

jkuech wrote:
If you are using the native applet then this is correct. XP cannot
distinguish between CD-R and RW as it has no packet writing capabilities, so
it treats them equally and, when you have finished a session, it closes and
finalises the disc so nothing further can be written to it. If you wish to
packet write you would need to purchase 3rd-party packet writing software.