If you still have problems afterwards, try connecting to good (as in fast and reliable) full nodes. I collected a list over time, if anyone reading wants to add some, feel free to contact me to improve it.
You can either add them with addnode IP add from console or add them in your config file [1] with addnode=IP.
last updated 2014.10.07
IP - location - owner* - speed - info/stats page**
213.165.91.169 - Germany, EU - shorena - 100 mbit/s - yes
84.200.34.113 - Freinsheim, DE, EU - Newar - 1000 mbit/s - yes
50.7.68.180 - New York, USA - Newar - 100 mbit/s - yes
5.9.24.81 - Germany, EU - zvs - unknown - no
178.79.173.71 - United Kingdom, EU - zvs - unknown - no
107.155.104.194 - Dalls, USA - zvs - unknown - no
106.185.32.195 - Japan, Asia - zvs - unknown - no
94.242.57.173 - Russia, Asia - zvs - unknown - no
* refers to a bitcointalk.org username
** same IP, port 80
Edit: updated the list
[1] https://en.bitcoin.it/wiki/Running_Bitcoin#Sample_Bitcoin.conf