If you are not a computer expert it is not advisable to install bitcoin-qt satoshi client or any bitcoin or alt-coin related program to store large amounts of coins. Call a computer expert, like me, to reinstall and secure your computer.
Read this page for all the security issues currently affecting bitcoin software.
The bitcoin software if downloaded from trusted websites is safe, however, your pc may not be!
YOU MUST USE:
-Windows 7 sp1 or newer version. Other OS, always the latest version.
-A clean system, format, reinstall, update, install antivirus.
-Online Antivirus as second opinion to confirm your computer is clean.
-This secure online wallets and enable secondary password.
-All online wallets, exchanges, mail accounts, with secured different password of +16 characters
-In all websites that offer 2FA or OTP, use it. It means second factor authentication, it's a one time password that uses your e-mail or your smartphone with google-authenticator or yubikey to prevent your account to be fully compromised.
-Never ever reuse your passwords. Do not store it with your browser unless you use firefox master password.
-Always keep your computer up-to-date, uninstall java, use a browser without flash, install adblock and noscript addon for firefox...
-Use a Secure password manager like kepass , lastpass with 2FA to keep track of your passwords, they even fill the password for you.
-Never ever use a pirate Windows XP with no automatic updates bought on the streets.
NMC:MxJdkECXLqYQfUTv4Pf2HWHNtv4pgUDtdt (need more devs!)
NVC:4PYwT4ec93Ue4Te72sSd3niFJAV4hmRjxu (Scam coin)
PPC:PHG7DU1yuRcSCqMZcerCZYSR5xd4B7PzLY ( POS:holders get+)
DVC:1PUmpY6wEAnS7DjfuWYTSJPUfzzsLu4w4m (btc/50000: as bad as dogecoin)
FRC:1LmnEtp8CpiDJqZtKxchqCGgzuGBDeWyu (Freicoin OMG demurrage)
CNC:CY47n4hss59Md4JRW49GFfBqBxYF8hcJks (China coin)