As mentioned in a knowledge base article describing a likely solution for most users.by MacFixIt's Topher Kessler, users may encounter issues when attempting to download Apps or App updates from the Mac App Store. Apple has now posted
When clicking the updates icon at the top of the Mac App Store window, the application may become unresponsive. This issue could be related to third party NTFS software including partitions with certain Windows NTFS file systems.
To alleviate the issue, navigate to System Preferences > Spotlight and click the Privacy tab. Add any of your NTFS file systems or connected drives by clicking the (+) button in the lower-left corner of the list window. You can also drag your volumes to the list.
"If you're using Boot Camp, select your BOOTCAMP drive or partition from the sidebar on the left side of the folder selection sheet, then click Choose, to prevent this issue from occurring."
Excluding your NTFS volumes should allow the Mac App Store to remain responsive. Should you still experience issues with the Mac App Store not being responsive during downloads,.
How has your experience with the Mac App Store been so far? What is your favorite feature? Let me know in the comments!