You are not providing enough information for us to go on.  First, what Poser version are you using?  This is important because the different version have different approachs towards solving particular problems.

Second, what OS are you running?  On PC's, WinXP is very forgiving if you place Poser within it's Program Files folder.  Vista, Win7 and Win8 will block your content from showing because of their UAC, a protective measure to saveguard files from viruses and malware.  If you did not select Poser 8's default installation under those conditions, then you will need to go back and reinstall the software, or create external runtimes to host your future installs.