Users have a limited amount of bandwidth, which is based on the amount of SP they have. When the network is busy, the amount of bandwidth per user goes down. Users who have low SP and have been transacting a lot (posting, commenting, voting, etc.) may run into temporary bandwidth limitations. The best thing to do is wait for a little bit (a few min, up to a few hours) and see if it starts to work after the network activity goes down. If you are doing anything excessive (following thousands of users, posting thousands of comments, etc), then it is best to cut down on your usage to stay within your bandwidth limits. You also have the option to purchase more SP. If you are not doing anything excessive and it becomes a major issue where it is happening constantly, or for prolonged periods of time, then post your account name here with a description of what is going on, and we will help try to figure out why you are being impacted.