/boot partition does not need to be mounted for normal operation - when used during boot time the boot loader (either grub or lilo - don't know which one you're using) will read the kernel and initial ramdisk directly from the drive, long before the mounting process. After bootloader hands over control to the init process accessing /boot is no longer necessary, as all the code from there has already been loaded to the initial ram disk.
If you are using a control panel then some CP operations may create a backup copy of a kernel.
If you keep your /boot umounted then anything trying to write to /boot will actually go to the root filesystem, so watch out for files in /boot. When something appears there while /boot is umounted you can trace which program wrote it then.
If so, odds are kernel updates are being added to your /lib/modules directory. Files in that directory must be manually deleted. Go into that directory and remove all files with version numbers lower than what is currently being used on the Server.
You can find the kernel version being used by looking in your 'root' WHM:
Server Status > Server Information > System Information
• PotentProducts.com - for all your Hosting needs
• Helping people Host, Create and Maintain their Web Site
• ServerAdmin Services also available