"Reader" Actually Created a New Partition

An update failed--possibly because the last PDF I had been reading was on a Truecrypt volume. I got an error message to that effect.

I followed the instructions provided for the error message number--at which time a new partition, labeled "OS," appeared on my Windows 7, 64, disk.

I tried to remove the partition; it failed. How could the error message instructions have created a new "OS?" If it counts, the region is striped on the Windows Disk Management program. I don't know what to do.

Thank you.