pdf file wont open

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows 7 Home Premium, Service Pack 1, 64 bit
Processor: AMD A6-3420M APU with Radeon(tm) HD Graphics, AMD64 Family 18 Model 1 Stepping 0
Processor Count: 4
RAM: 5606 Mb
Graphics Card: AMD Radeon(TM) HD 6520G, 512 Mb
Hard Drives: C: Total - 459837 MB, Free - 391330 MB;
Motherboard: Acer, Aspire 5560
Antivirus: PC Cleaner Pro, Updated: Yes, On-Demand Scanner: Disabled

when I try to open certain pdf. files they just bring up a white screen with a black x in the top left hand corner
some are on the internet others on a cd
the ones on cd will open if I go into adobe icon on my desktop and open them through that
any ideas as to what is wrong will really be appreciated as is drivin me mad
thank you