Last week we had another new members spike, with one of the days over 8,000 accounts, if I remember well. This new wave of users started to interact with the platform quite heavily and very soon many of them ran into bandwidth problems. Which means they couldn't post, comment or upvote anymore.
You Do Have A Bandwidth Allocation On Steemit, You May Not Know About It
If you never ran into this problem, maybe it's time to know abut it. "Bandiwdth" is described in the Steem white-paper as a way to mitigate spam and network abuse. Every time you perform a transaction on the Steem blockchain, your bandwidth is affected. If you perform more transactions than your current bandwidth allows, you won't be able to access the system.
In layman terms, it goes like this: the more SP you have, the bigger your bandwidth allocation, hence, the more you can interact with the platform.
Since there is no message on the user account page about this, it may get really confusing for newcomers. So I opened a Github issue or Condenser (the UI on top of the Steem blockchain used by Steemit.com) suggesting a message for new users, here's how it looks:
If you think this will be useful, you can support it by upvoting it on Github, or sharing this post in your network, to raise awareness about it.
Steem on!
I'm a serial entrepreneur, blogger and ultrarunner. You can find me mainly on my blog at Dragos Roua where I write about productivity, business, relationships and running. Here on Steemit you may stay updated by following me 
https://steemit.com/~witnesses
If you're new to Steemit, you may find these articles relevant (that's also part of my witness activity to support new members of the platform):