I recently upgraded my copy of Adobe Reader to Adobe Reader X, the new version that sandboxes the PDF reader. I immediately had problems with PDFs that I tried to open from the internet. I uninstalled Reader X and reinstalled to no avail. I suspected that there might be an issue between Sandboxie and Reader X and searched. Immediately I found that the problem had been reported back in November of last year and a newer version of Sandboxie fixed the problem. That puzzled me a bit as I had received a notification from Sandboxie and told it to upgrade. What I had not noticed was that the upgrade failed. After a few failed attempts to get Sandboxie to upgrade using its internal mechanisms I downloaded the current version of Sandboxie and manually installed it (after closing the Sandboxie control box).
When the new version launched it detected that Adobe Acrobat Reader, ESET NOD32 Antivirus, Windows Live, and Enhanced Migration Experience Toolkit v2.0 (Microsoft EMET) were present and suggested that I allow it to configure Sandboxie for compatibility with these programs. I did allow that and now I am able to open PDFs with Reader X.
For those of you who may not be familiar with Sandboxie, you can find it at www.sandboxie.com. Sandboxie is a program that helps keep your computer safer by providing limiting how much damage malicious software can do. If you are browsing the web in a sandboxed browser then if you get infected simply deleting the contents of the sandbox will remove the infection in all cases I am aware of. Sandboxie will not protect you against phishing attacks, that is not what it is designed to do. Further, if you get infected with a keystroke logger and then go to your bank, your username and password can be compromised. With the paid version of Sandboxie you can have multiple sandboxes. I find this very handy for a number of things. I use one sandbox for things like online banking. I still delete the sandbox on a regular basis though. I use one sandbox for sites I think might be particularly dangerous (and that is inside of a virtual machine). I can also log on to multiple Yahoo accounts at the same time by running them in different sandboxes.
If you use Sandboxie is worth checking to be sure that you have the most recent version.
Director of Technical Education
Author ESET Research, We Live Security