lot of times , its fine generating download links , but at very peak times it gives me this error

Error happened when generating Download Link.
Please try again or Contact administrator.
()


Why is that and how can i fix it?

im currently using Intel i7/Xeon 1G-N1 CPU : Intel Core i7 or Xeon CPU Power : 4x2x2.8 GHz RAM : 24 GB HDD : 2 x 2 TB Uplink : 1 Gbit Dedicated Bandwidth : 100TB Location : Europe 2 Free Extra IP address and plannning to buy this for fileserver and the top one will be the webserver. Intel i7/Xeon 1G...

Hello, my site was working perfect and then it got lots of traffic and i have only 1 server, site is loading really really slow, what shall i do? add more servers?