Why NTFS write softwares cause some certain problems? After installing NTFS write software on my mac, I found two problems.


The Windows system in bootcamp does not show in the startup disk in Settings app.
Parallels Desktop can't suspend the Bootcamp virtual machine because such software installed.


Both the problems can be solved by removing the software.

What's the reason behind this?
You do not mention what software you're using to mount the NTFS volume read/write in OS X, nor which version of Parallels you're using, nor do you say what model Mac you have.  This is important to give you accurate information.

Paragon NTFS works with Parallels just fine.  MacFUSE or other NTFS read/write utilities do not.  Also, Parallels 8 and lower have issues with Paragon HFS if you have that installed on the Windows side.

Also, you should never suspend the Parallels Boot Camp VM.  If you attempt to boot to Windows via Boot Camp while the Parallels VM is suspended, you can cause data corruption.