Why don't you just wait for the second bug fix to come out?
The FIRST bug fix typically fixes common bugs -- and who knows, yours may be among them -- but breaks things that once worked just fine.
The SECOND bug fix generally fixes the bugs created by the first bug fix.
In addition you can probably look forward to a third bug fix, which addresses more exotic & rare bugs.
What to do in the meantime? Use an earlier version.
If I were you, I wouldn't wait for the second bug fix as there's so much better about this release compared to previous ones. However, you may need to wait for the first bug fix.
There is an issue that the AE team is aware of where a preview can hang in certain cases on Macs. If I were you, I would file a bug report ASAP to make sure that if your bug isn't the one I'm thinking of that it gets included in the first bug fix update.
I'd suggest you install the latest update that came out last night: After Effects CC (November 2017) Bug-Fix Update Is Now Available
This update is 14.0.1 and should be a bug fix for this and several other disturbing issues - especially for Mac users. It does not fix all the bugs that are new with the CC 2017 release (Known issues in After Effects CC 2017), but it does fix some issues that have been plaguing After Effects since the first parts of the new architecture showed up in the CC 2015 release.
If you can't see the update yet, you may need to wait a while until you see it as it can take up to 24 hours to populate an update across all the data centers. You may need to log out, relaunch the Creative Cloud app, and log in again.