I don't believe there is a "hash check and start" option available on the client. Sometimes when you click start, THEN it starts to hash check and THEN after it is done, will the torrent proceed to begin downloading. However, if it is downloading, but you think it needs to do a hash check because you see something amiss, if you stop the torrent and then hash check it, it will not download afterward.
Maybe i'm confusing you a bit so here is an example.
Let's say i have a torrent that is 34.6% downloaded, then someone hits the cable out of an external hard drive where the torrent was downloading to. (Now you'd see a red X). You plug back in your hardrive, it has the same drive letter as before so the download location is the same, but you clicked the torrent to start and now instead of startiing from 36.4% it starts to download from 0%. Obviously a hash check is needed at this point, so you stop the download and then you manually hash check the task. However, it is a very big file, 15 gigs and you want the torrent to start as soon as it finishes the manual hash checking but it won't do that because when it is done it will enter the stopped state.
I hope that example helps, adding a "manually hash check and continue downloading" option would be greatly appreciated, especially for people who want to download overnight while they sleep and have big tasks.
If it is possible to do this already however, please let me know =)