Comodo Installation under Windows 7

CTM Installation from CD works ok. → Restart required. → System will not start because of Boot error ?
→ new installation of Windows 7 necessary if no other backup ( Acronis ) available.

CTM works on the second machine ( Windosw 7 64-bit ) perfectly.
Any suggestions to solve the problem ?
Would appreciate some help because I like the product.

Regards, chitah