Windows 7 Can't Open Pictures or New User Accounts

[haplyss]

OS Version: Microsoft Windows 7 Home Premium, Service Pack 1, 64 bit
Processor: Pentium(R) Dual-Core CPU E5300 @ 2.60GHz, Intel64 Family 6 Model 23 Stepping 10
Processor Count: 2
RAM: 6109 Mb
Graphics Card: Intel(R) G45/G43 Express Chipset, -1265 Mb
Hard Drives: C: Total - 938406 MB, Free - 886307 MB;
Motherboard: Gateway, EG43M
iAntivirus: Microsoft Security Essentials, Updated and Enabled

My computer suddenly tells me it can't open my pictures on one of my user accounts by asking what file do I want to use to open it or to go online to search for an opening file. I tried to start a new user account, and I'm told I need to tell what file I want to use to complete and open this account. Does anyone out there have any ideas what may be causing this problem? I'll appreciate all and any answers.

Thankl you

haplyss

 

[tbint]

simple question, what is the file extension of the picture? jpg, png, gif?

 

[Pauli]

Your computer "suddenly" tells you... Done some changes, have you?