Text getting very buggy

Sometimes, the text when you have any language that has the bigger letters on gets very buggy and barely readable. This bug happens with any texture pack (including default). I don't think you have to do something particular to reproduce this bug. The console did not say anything special. The only Java exception I saw was:
Client> java.io.IOException: Stream Closed
Client> at java.io.RandomAccessFile.seek(Native Method)
Client> at adu.a(SourceFile:308)
Client> at adu.a(SourceFile:251)
Client> at adv.close(SourceFile:232)
Client> at java.util.zip.DeflaterOutputStream.close(Unknown Source)
Client> at java.io.FilterOutputStream.close(Unknown Source)
Client> at adx.a(SourceFile:140)
Client> at adx.c(SourceFile:128)
Client> at amj.b(SourceFile:30)
Client> at amj.run(SourceFile:23)
Client> at java.lang.Thread.run(Unknown Source)
I do not think this exception has anything to do with the buggy text. It (the exception) happens every time I run the snapshots, I think.