Such as: [PAR: 2800 of 2900\ D:125 DL:1 Inc0 P:0 R:4 N:6
I should post a sticky about this.
[PAR: 2800 of 2900] - You've downloaded 2800 of 2900 PAR blocks. You need another 100 blocks or 100 repair blocks to finish the download.
D:125 - 125 files have downloaded.
DL:1 - 1 file is still in the process of downloading.
Inc 0 - 0 files are incomplete (meaning the data is all there about how to download). It doesn't mean the files are good, just that the information to download the file is all there.
P:0 - 0 files are paused
R:4 - 4 retries so far
N:6 - 6 seconds till the next retry.
1 - In a case like this, I'd right click the main item and check the files to see which ones are bad.
2 - I'd click the + icon and look at the files.
It suggests you don't have enough data to finish the download. Finding out which files are messed up/missing might let you do something to fix it.