Bug in computer set creation - TMG Beta 2

I have run into what I think is a bug in the computer set portion of TMG
Beta 2.

1. Create a computer set
2. Click Add > computer > input info for one just one IP address. I.E.
Computer name "Computer IP one", IP address "202.75.200.23". Click OK
3. Click Add > subnet > input info for IP subnet I.E. Computer name
"Computer subnet one", IP network address "61.224.0.0/24". Click OK

4. Click ok and save the whole computer set
5. Reopen the set
6. Either change the name of anything above or add something new.
7. Try to save it.
8. You get an Error: 0xc00403cf saying "The IP mask specified for the object
is invalid. The error occurred on object '61.224.0.0' of class 'Subnet' in
the scope of array 'TMGCOMPUTER'."
9. If you then click OK, you get an Error: 0xc0040304 saying "Later "The
object is not valid""
10. If you kill the address that has the subnet line, it will save just
fine. It does not matter what the subnet line is...it can be anything...it
always gives an error.

Any ideas?

Arch