Have you tried opening the PST on another computer, also was it created in Outlook 2007 as it may no be compatable.
MAke sure you computer meets these requirements,
500 megahertz (MHz) processor or higher
Memory 256 megabyte (MB) RAM or higher
Hard disk 1.5 gigabyte (GB);
Microsoft Windows XP with Service Pack (SP) 2, Windows Server 2003 with SP1, or later operating system
Taken from http://office.microsoft.com/en-us/pr...668651033.aspx
NOTE: if you have Microsoft Office Outlook 2007 with Business Contact Manager it needs a higher spec PC