Performance issues/failure when working on shared drives

We're experiencing a bizarre issue that has only begun within the past few days. The only change that has been made is a firmware upgrade on our Sonicwall, but the issue is present both on the local network as well as VPN users. What we are experiencing is extreme lag or inability to complete tasks while working with the files located on our DC.

The specific example I can provide has been reproduced using Acrobat Standard XI and DC both on the local network and over VPN using multiple user accounts. We open a PDF, use the Insert Pages function, select multiple files and it processes most of them before it just hangs and eventually crashes. It seems to have an issue with a JPG (with geocaching information) that is just under 4MB. I try to convert the JPG to PDF individually using the right click menu and it creates a PDF with only maybe 5% of the image converted.

If I move the files to a local folder and go through any of the steps above, it works flawlessly. I thought that the connection to the server may be dropping out, so I ran a continuous ping while performing the steps and there are no drops. I've done it both by name and IP to try and eliminate a DNS issue. I've also run through the steps using different files, but the same process and encounter the same issue.

I appreciate any help that can be provided.